WASHINGTON -- Why aren't Democratic presidential candidates talking more about foreign policy?

Are they being shrewd in playing down a divisive concern that is not at the front of voters' minds, or are they missing an opportunity? The right answer is: Both.

A new study by the Center for American Progress (CAP) finds that when Americans look at the world, they think primarily about how their government can keep them safe and bolster their economic opportunities. "At the most basic level, voters want U.S. foreign policy and national security policies to focus on two concrete goals: protecting the U.S. homeland and its people from external threats -- particularly terrorist attacks -- and protecting jobs for American workers," the report finds.

And if the Democrats running for president are concentrating their energies on domestic goals, well, that is what the voters want, too.

The progressive group's survey "provides overwhelming evidence that American voters want the United States to be 'strong at home' first and foremost to help it compete in the world." They "express a clear desire for more investment in U.S. infrastructure, health care and education -- and less of an exclusive focus on military and defense spending -- as part of a revamped foreign policy approach that gets America ready to compete with other countries."

So why not highlight "infrastructure, health care and education" and leave foreign affairs by the wayside? Because the survey also found that foreign policy is a genuine vulnerability for President Trump. While voters narrowly (50% to 48%) approved of the president's handling of the economy, a large majority (57% to 40%) disapproved of his handling of foreign policy. Just 31% of voters said that "The United States is more respected in the world because of President Trump's leadership," while 62% picked the other option: "Under President Trump, America is losing respect around the world and alienating historic allies."

John Halpin, a CAP senior fellow and lead author of the study, pointed out a paradox: Most Americans dislike Trump's approach, but his distance from the old foreign policy establishment is a political asset.

"The language and policies of the foreign policy expert community simply don't work with many voters," Halpin said in an interview. "People are confused by abstract calls to defend the liberal international order or fight authoritarianism. The lack of clarity about goals and visions on the center-left opens the door for Trump-like nationalism to take hold, even though the president himself is unpopular."

One of the study's striking innovations is a new typology defining how different groups of Americans view foreign policy. The bottom line: Our nation is fractured.

Using 20 survey questions to capture voters' priorities and values, the researchers found that the largest group, 33% of voters, could be described as "Trump Nationalists." They prioritized military spending, fighting terrorism, focusing on concerns at home and opposing the United States' role as the world's policeman.

Close behind -- and very different -- were the "Global Activists" at 28%. They emphasized working with allies on climate change, disease, poverty, inequality and equal rights and stressed the importance of international institutions.

The smallest group reflected the attitudes of those who tend to dominate mainstream foreign policy debates. "Traditional Internationalists" (18%) focused on the U.S.'s duty to engage in world affairs, the benefits of trade and alliances, the importance of defending democratic values, and the obligation to use force in response to threats. (The "Foreign Policy Disengaged," at 21%, had few intense views.)

Taken together, the Activists and the Internationalists outnumber the Nationalists by a margin of nearly 3-to-2. But the fissures between advocates of newer and older forms of global engagement show how hard creating a consensus against Trumpism could be. An analysis undertaken by CAP at my request demonstrated that a bipartisan foreign policy is not in the cards. Among Democrats, 48% are Global Activists and 10% are Trump Nationalists. Among Republicans, 61% are Nationalists, and only 7% are Activists. Internationalists account for roughly a fifth of each party.

Of the 2020 Democratic candidates, Sens. Elizabeth Warren and Bernie Sanders have made the most substantial efforts to link progressive economics with opposition to authoritarianism and kleptocracy abroad. Halpin argues there is room for other contenders to elaborate a "strong at home, strong in the world" vision.

But there will be powerful incentives for them to avoid aggravating Democratic foreign policy rifts. And traditional internationalists face enormous challenges in selling concepts they hold dear to an electorate weary of war and anxious about an increasingly competitive world.

— E.J. Dionne is on Twitter: @EJDionne.