Throughout his insurgent campaign for the Democratic presidential nomination in 2016, one of Bernie Sanders’s chief rallying points was to question why the United States is the “only major country on Earth not to guarantee health care to all people.” Having taken the issue into the political mainstream, the independent senator from Vermont is turning his broad idea into something more concrete by rolling out a “Medicare for All” bill on the floor of the Senate on Wednesday. 
 
 Related: If Bernie Sanders wants to win 2020 election, he needs to control his supporters, Democrats say 
 
 Even Sanders has acknowledged that it’s “obvious” the bill has no chance of passing with the Senate (and House) controlled by Republicans. But he has already succeeded in pushing the issue further into the spotlight and pressuring Democrats to jump on board. Support for the bill has become a practical litmus test for the party’s 2020 presidential hopefuls. 
 
 After California Senator Kamala Harris signed last month, other potential 2020 candidates—Senators Cory Booker, Elizabeth Warren and Kirsten Gillibrand—were among those to take the number of bill co-sponsors to 11 as of Tuesday afternoon. 
 
 The simple tenant of the proposal is to put in place in the U.S. a single-payer system akin to that used in the U.K., France, Australia, Canada and others. These can differ from fully government-run national health services, as in the U.K., to France’s public/private hybrid. Whatever route they take, though, they offer universal health care and no requirement to get insurance through an employer. In the U.S., the current Medicare safety net, which now covers only people over age 65, would apply to all Americans. 
 
 “Health care must be recognized as a right, not a privilege,” Sanders argues. “Every man, woman and child in our country should be able to access the health care they need regardless of their income. The only long-term solution to America’s health care crisis is a single-payer national health care program.” 
 
 Sanders has said that the plan would in large part be paid for by a progressive tax system that would have the richest households paying more income, capital gains and estate taxes, among others. Existing health care expenditures would also go toward the plan. According to Sanders, his plan would save the American people and businesses $6 trillion over the next decade. 
 
 While there is widespread evidence to support the notion that a single-payer system is far more cost-effective than the current model in the United States, the exact savings under Sanders’s plan remains a topic for much debate. 
 
 Still, although Republicans and even more moderate Democrats aren’t rushing to sign onto a single-payer system anytime soon, polls have showed that Americans have already moved in that direction. A June 2017 Pew Research Center survey found that 60 percent of Americans said the federal government should be responsible for ensuring health care coverage for all Americans. 
 
 Update: An earlier version of this story misspelled the name of Kirsten Gillibrand. This has been corrected. ||||| (CNN) When Sen. Bernie Sanders did this in 2013, he did it alone. 
 
 On Wednesday, nearly four years later, Sanders introduced a new "Medicare for all" health care bill with a third of the Senate Democratic caucus by his side. 
 
 Flanked at first by New York Sen. Kirsten Gillibrand and Connecticut Sen. Richard Blumenthal, Sanders called the costs of the current system "insane and unaffordable," promising that the average family would benefit financially under his plan "because you will no longer be writing checks to private insurance companies." 
 
 For those whose taxes would go up, he added, "that expense will be more than offset by the money are you are saving with the elimination of private insurance costs." 
 
 Sanders said he planned to take the bill on the road to "every state in the country and hear what the people have to say" for a roving national workshop. But the outreach came with a warning. He fired a shot across the bow of Republicans likely to oppose the bill, saying the GOP had "no credibility on the issue of health care." 
 
 "To my Republican colleagues, please don't lecture us on health care," Sanders roared to applause from the dozens of activists in the room. "In the last few months, you, the Republican Party have shown the American people what you stand for" by largely voting to dismantle Obamacare. 
 
 Taking her turn, Massachusetts Sen. Elizabeth Warren framed the push for single payer as the latest step in a long liberal project to expand access to medical care -- from Franklin Roosevelt's social security to Medicare and Medicaid under Lyndon Johnson and, most recently, Barack Obama's signature legislation. 
 
 "But we are here today to take another step," she said. "We will not back down in our protection of the Affordable Care Act, we will defend it at every turn, but we will go further -- we will go further and we will say that in this country, everyone gets the right to basic health care." 
 
 Before Sanders' remarks, supporters shared personal, often visceral accounts of doctors currently struggling to provide care and patients in need. An oncology nurse drew gasps in the room as she recounted the story of a cancer patient who could not afford to continuously empty the fluid building up in her lungs. The price of drainage bags, she said, was only covered in part by insurance, forcing the woman to ration her use. 
 
 The legislation unveiled on Wednesday afternoon in Washington arrived a little more than six weeks after the party's all-hands fight to preserve Obamacare secured a narrow reprieve on the Senate floor . Sanders' plan, though dead-on-arrival in a Republican-controlled Congress, offers a blueprint for fundamentally reshaping the American health care system by moving the country to a government-run, single-payer program. 
 
 Under Sanders' proposal, Americans would receive a "Universal Medicare card" that would be a ticket to comprehensive health care services, including hospital stays, doctor visits, substance abuse treatment, dental, vision and reproductive care -- including abortion. 
 
 However, consumers may have to pay up to $250 out-of-pocket for prescription drugs, with incentives to use generic medications. Sanders, who's been vocal about lowering drug prices, would allow the government to negotiate with pharmaceutical companies. 
 
 Long-term care, which Sanders had included in the version he unveiled during his presidential campaign last year, will not be covered. It will be addressed in separate legislation, an adviser to Sanders told CNN. 
 
 The bill calls for the elimination of premiums for private health insurance, deductibles and co-pays. However, most Americans and businesses will pay what Sanders says is a much smaller share of their income to fund the program. 
 
 While the new legislation has not yet been scored, the program Sanders pitched on the campaign trail came with an estimated annual price tag of nearly $1.4 trillion, to be paid for in part by a proposed new 2.2% income tax on all Americans, a 6.2% levy on employers and a further round of tax hikes on the wealthy. 
 
 California Sen. Kamala Harris made the business-friendly case for single-payer. (Or, as one leftist activist in the room grumbled afterward, "the neoliberal case.") 
 
 "Let's give the taxpayer of the United States a better return on their investment," she said. "Why? Because 'Medicare for all' stands for the proposition that all Americans from the day of birth, throughout their lives, will have access to health care." 
 
 The talk on Wednesday was broad, with little mention of the financial mechanics needed to propel such a massive program. But Sanders' plan does address one of the stickier questions facing such proposals: how to phase out the current system, which depends primarily on employer-sponsored private plans, without creating a disruption in care. 
 
 The answer, according to this new version of the bill, is to roll it out over a four-year transition period, a process Gillibrand and her office had a big hand in crafting. 
 
 The law would beef up Medicare -- adding dental, vision and hearing aid coverage -- in its first year, while reducing the eligibility age to 55. Children, up to age 18, would also be offered immediate access to the government-run plan. Over the next two years, the Medicare age would drop to 45, then 35 years old. By the fourth year, everyone would be eligible. 
 
 Despite the considerable legislative obstacles in its way, single-payer as a concept is gaining traction among the public. Some 53% of Americans support a national health care plan , according to a June poll by the Kaiser Family Foundation. That's up from 50% last year and from 40% between 1998 and 2000. 
 
 It is also notably increasing in popularity with some of the most ambitious Democratic officeholders -- a group of Senators possibly looking to run for the party's presidential nomination in 2020. 
 
 Harris was the first to announce plans to cosponsor the bill, followed by Warren. New Jersey Sen. Cory Booker and Gillibrand made their plans public on Monday and Tuesday. The names, some expected, others less so, rolled in right up to a few hours before the event, when New Hampshire Sen. Jeanne Shaheen announced her support. 
 
 Notable absences, however, included Senate Minority Leader Chuck Schumer of New York, Ohio Sen. Sherrod Brown, California Sen. Dianne Feinstein and the party's 2016 vice presidential nominee, Virginia Sen. Tim Kaine. Of the latter three, all up for reelection in 2018, only Brown is expected to face a serious Republican challenge. 
 
 Single-payer activists, mostly from the progressive grassroots movement that fueled Sanders' 2016 presidential campaign, are delighting in a sense of momentum after years stuck on the margins of the debate. 
 
 "This is an especially gratifying moment for the tens of thousands of nurses across the US who have dedicated years of effort to transform our health care system from an profiteering industry based on greed and suffering to patient need and healing," National Nurses United Executive Director RoseAnn DeMoro said in a statement. 
 
 She called the bill's introduction a "direct product of how Sen. Sanders made Medicare for all, and healthcare as a human right, such a signature issue of his campaign." ||||| Vermont Sen. Bernie Sanders and his call for a government-run health care system are back. On Wednesday, he is laying out a bill that proposes “Medicare for all,” replacing a U.S. health care system dominated by employer-provided insurance — with lots of assorted co-payments and deductibles — to a single-payer approach in which higher taxes fund a system where individuals don’t pay directly for health care. Influential Democratic senators and potential 2020 candidates Cory Booker (New Jersey), Kirsten Gillibrand (New York), Kamala Harris (California), Jeff Merkley (Oregon) and Elizabeth Warren (Massachusetts) have embraced the idea. 
 
 “Medicare for all” is going absolutely nowhere anytime soon under a Republican-controlled Congress and President Trump. But here’s the big question: Is it going to become one of the central goals of the Democratic Party and a defining feature of the campaign of whichever Democrat is the party’s nominee in 2020? This seems very likely, at least right now, given the political forces pulling Democrats to the left. But I’m not totally sure, mainly because there are some clear political and policy reasons for Democrats to avoid becoming the party of single-payer. 
 
 Why the Democratic nominee may have to strongly embrace Medicare-for-all 
 
 
 
 1. Some of the party’s most popular figures are already behind it. 
 
 FiveThirtyEight’s Nate Silver and Vox’s Matt Yglesias have argued that Sanders is, at least right now, the front-runner for the Democratic nomination for president. If Sanders, who is 76, opts not to run, the 68-year-old Warren seems like an obvious person for Sanders backers to embrace, as she shares many of the same liberal and populist positions. Harris, the daughter of an Indian woman and a Jamaican man, was elected district attorney in San Francisco and has won statewide election three times in California, which is about 40 percent Latino. A candidate with appeal to Asian, black and Latino voters as well as upper-income whites in cities like San Francisco would be formidable in a Democratic primary. I think it’s fair to say that all three of these senators would rank among the top 10 current contenders for the Democratic nomination. Booker is rumored to be considering a run as well. (The online betting site PredictIt ranks these four as among the top five people likely to get the Democratic nomination in 2020, along with former Vice President Joe Biden.) 
 
 So Booker, Harris, Sanders and Warren already being for Medicare-for-all greatly increases the chances of the Democratic nominee in 2020 supporting this policy, simply because one of that quartet has a strong chance of being the nominee. And staking out this position, well to the left of where the party was even last November, puts pressure on Biden, New York Gov. Andrew Cuomo and other Democrats who might be considering a 2020 run. Even if one of those candidates privately disagrees with the merits or the strategy of pushing Medicare-for-all, he or she might opt to support the idea to avoid being tagged as insufficiently liberal and therefore out of step with the party’s activist base. 
 
 This is how presidential nomination processes often work. In the campaign for the 2008 Democratic nomination, John Edwards came out with a comprehensive health insurance plan, effectively forcing Barack Obama and Hillary Clinton to do the same. (The Edwards plan, with its individual mandate and emphasis on creating health insurance marketplaces, was one of the building blocks of what eventually became the Affordable Care Act.) 
 
 This intra-party competition is the biggest and clearest reason to assume Medicare-for-all will become party dogma. 
 
 2. The Democrats are becoming a more liberal party. 
 
 In 2012, according to the Pew Research Center, about 19 percent of self-described Democrats considered themselves conservative, about 36 percent said they were liberal, and about 41 percent said moderate. Today, a plurality of Democrats (48 percent) describe themselves as liberal. A shift to Medicare-for-all would be in line with this march to the left. 
 
 And the party’s elected officials are headed there, too. The new “Better Deal” agenda that congressional Democrats unveiled in July includes a number of Sanders-inspired populist ideas. The party rebranding effort, for example, calls for requiring prescription drug companies to submit an explanation to the U.S. government if they increase the price of a drug by too much. 
 
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 In this environment, it is much easier to see a centrist Democrat like Cuomo essentially accepting Medicare-for-all as a stance he must take rather than pushing Democratic activists away from Medicare-for-all. 
 
 3. The Obamacare experience is moving Democrats. 
 
 In 2009 and 2010, when he was stumping for the Affordable Care Act, Obama often highlighted the private marketplaces that would be set up under the law. He mentioned how the ACA would expand Medicaid less often, perhaps with an eye on winning over more independent or conservative-leaning voters who might be leery of more government intervention in the health care system. 
 
 But in practice, the private marketplaces have been beset with high rates and insurers fleeing the system, while Medicaid expansion has been popular. This year, as Republicans sought to repeal the ACA, Democrats hammered them on Medicaid, which would have been cut by billions of dollars in the GOP repeal proposals. This defense of Medicaid by Democrats seemed to force even Republican senators like Nevada’s Dean Heller to say they were committed to defending the program. 
 
 “One thing has saved the Affordable Care Act from Republicans’ efforts to repeal it: When the votes counted, at least three Republican senators — along with every Democrat in the Senate — could not accept massive cuts to Medicaid,” wrote Mark Schmitt, who runs the Political Reform program at the D.C.-based think tank New America and was a longtime Democratic staffer on Capitol Hill. 
 
 Putting more people on government-funded health care programs is an idea that Democrats often favor but sometimes sidestep because they think it is too politically difficult to get adopted. (Obama, in an interview with Vox in January, essentially said that he thought a single-payer system would be more effective, but didn’t think it was possible to get that passed in 2009 or 2010.) The ACA experience has led Democrats — even those who strongly promoted and defended Obamacare — to argue that the ACA has not fixed enough of the country’s health care problems and push for a more comprehensive solution. 
 
 Party officials now believe that the public may be open to such a proposal. “It’s always the biggest applause line,” U.S. Rep. John Yarmuth of Kentucky, a Democrat, told me. 
 
 Warren, in a blog post on her website, carefully praised the achievement at the center of Obama’s legacy while signaling a desire to move beyond it, writing: “We owe a huge debt to President Obama. Because of the Affordable Care Act, health care coverage is better. … But there’s so much more we could do right now to bring down the costs of quality health care for every American.” 
 
 Why the Democratic nominee may be not strongly for Medicare-for-all. 
 
 
 
 1. A Medicare-for-all candidate may not win the primary. 
 
 There was a lot of talk in 2013 about how the Republican presidential nominee three years later would be more liberal on immigration issues than past candidates because of how badly Republicans did in the 2012 election with non-white voters. One of the people pushing that way on immigration (Marco Rubio) also seemed a likely top-tier presidential candidate, the way Booker, Harris, Sanders and Warren are. We know how that turned out. 
 
 Some combination of Booker, Harris, Sanders and Warren may not run for president. They might all run and lose. And the candidate who wins the Democratic nomination could be someone who breaks from the Medicare-for-all view, or at least says that he or she is open to other ideas to improve America’s health care system. Maybe that will be a figure like Biden or Colorado Gov. John Hickenlooper, either of whom might run for president and could position themselves as the center-left alternative to the more liberal candidates. In fact … 
 
 2. Medicare-for-all is not the only way to expand government-run health insurance. 
 
 Liberal wonks, such as Paul Krugman, are not so sure about Medicare-for-all. They argue that such a system is actually extremely complicated to create and that the final product might irritate the millions of Americans who have insurance through their employer and like it. 
 
 So some Democrats are proposing ideas like Medicare-for-some (U.S Sen. Chris Murphy of Connecticut) or Medicaid-for-some (U.S. Sen. Brian Schatz of Hawaii). The general idea is that people who are uninsured could buy (or be enrolled for little cost if they don’t make much money) into these programs. 
 
 This kind of a policy would be less of a shift to the left. Obama proposed a “public option” in 2009 that would have been similar to the ideas of buying into Medicare or Medicaid that Murphy and Schatz are touting. He dropped the idea after some more conservative Democrats opposed it, but by the end of his presidency, Obama had strongly embraced the idea. Hillary Clinton included a public option in her 2016 platform, though it was not a big feature of her campaign. 
 
 Maybe a more moderate Democrat could campaign on expanded Medicaid and Medicare but downplay the “for all” part. And that might have appeal because … 
 
 3. Many Democratic voters are not liberal. 
 
 I described earlier how liberals are ascendant in the Democratic Party. But according to Pew, the combined group of self-identified moderates (36 percent) and conservatives (15 percent) is as large as the liberals. Whites, people with college degrees, and millennials are disproportionately liberal, while other demographics in the party are not. According to Pew, 55 percent of white Democrats consider themselves liberal, compared with 28 percent of black Democrats and 41 percent of Latinos. About 60 percent of Democrats with postgraduate degrees consider themselves liberals, compared with about 37 percent of Democrats with a high school degree or less. 
 
 You could imagine New Orleans Mayor Mitch Landrieu pitching himself as the candidate who can appeal to working-class whites and more moderate Democrats. And part of that pitch could be running on a health care plan that is more likely to be passed into law than Medicare-for-all. 
 
 In June, Pew polled Americans on creating a “single-payer” health care system. Only 33 percent of the public overall supported the idea, although 52 percent of Democrats backed it. I assume Democratic support for Medicare-for-all will grow with more leading figures in the party embracing it. Also, the poll asked people about a single national health insurance system run by the government, not “Medicare-for-all,” which I suspect is a much more popular notion. But the survey did not ask respondents about “Medicare-for-all” versus “Medicare-for-some,” which might also be a popular idea. So public opinion on this issue could well shift in a number of directions. 
 
 I’m inclined to think that whoever receives the Democratic nomination in 2020 will support Medicare-for-all, either because he or she truly believes in the idea or because party politics effectively force this. I’m not so sure that this idea will ever become U.S. policy — or even come to a vote in Congress. But its embrace by Booker, Harris and Warren less than a year after the election tells us two important things about American politics right now: Sanders lost the Democratic Party’s nomination, but he may have emerged as the party’s intellectual leader. And the Democrats appear to have concluded from 2016 that, at least on economic issues, they should move left, not right.
– Bernie Sanders rolled out his vision to overhaul the health care system on Wednesday, one in which everybody would get their insurance from the government through Medicare instead of through their jobs or a private insurer. Sanders calls it the Medicare for All Act of 2017, but you'll also hear phrases such as "single payer" and "universal health care" used to describe it. One key part missing: details on how to pay for it, though Sanders plans to release a separate paper on that, reports the Wall Street Journal. Coverage: The basics: Per CNN, everybody gets a "Universal Medicare card," which would be used to cover all health bills, from surgeries to dental care to substance abuse treatment. Co-payments would go away, and people would pay premiums based on their incomes, reports the AP. Private insurers would still exist, but for things such as elective plastic surgery or, sometimes, to act as middlemen between the government and hospitals or doctors. A 'right': Sanders makes his case in an op-ed in the New York Times. "Guaranteeing health care as a right is important to the American people not just from a moral and financial perspective; it also happens to be what the majority of the American people want." 'Single payer': David Leonhardt of the New York Times has a Q&A on the fundamentals, including the basic question of what the term "single payer" means. In short, it "describes a system in which only one entity—the government—pays medical bills. If all Americans had Medicare rather than insurance through their jobs, it would be a single-payer system." Vox says Sanders' system is far more generous than single-payer plans in Canada and elsewhere. The cost: This could cost hundreds of billions of dollars more per year, per the Journal. Details are yet to come, but Sanders envisions a progressive tax increase, with the wealthy paying more income, capital gains, and estate taxes, reports Newsweek. The senator says higher taxes for families would be offset by the fact that they no longer have to buy insurance. Still, in regard to single-payer systems, "no one—including Sanders—has truly reckoned with how to pay for whatever system they might support," writes Mike Allen at Axios. Litmus test? By all accounts, the chances of it passing a GOP-controlled Congress are precisely 0%. But it's turning into a political litmus test of sorts for Democrats, reports the Washington Post. Sanders has the support of 15 Democratic senators so far, including all of those seen as potential 2020 presidential candidates. Co-sponsors include Elizabeth Warren, Kirsten Gillibrand, Cory Booker, and Kamala Harris. But many prominent Democrats are not on board, at least yet, including Nancy Pelosi, Chuck Schumer, and those in tough re-election fights, reports Politico. The politics: No, this isn't going to pass, "but here's the big question," writes Perry Bacon Jr. at FiveThirtyEight. "Is it going to become one of the central goals of the Democratic Party and a defining feature of the campaign of whichever Democrat is the party's nominee in 2020?" As of now, this "seems very likely," as the Democratic party seems to be gravitating to the left. But Bacon lays out the political and policy reasons why Democrats might avoid "becoming the party of single payer." Relishing the fight: Republicans see a chance to pounce. "We welcome the Democrats' strategy of moving even further left," says Katie Martin, spokesperson for the Senate GOP's campaign organization, per the AP.