There is speculation whether impeachment will hurt some House Democrats from marginal districts; no doubt, a few will squirm.

If, as seems likely, the House votes to impeach Donald Trump, and it goes to the Senate for a trial, a handful of Republicans there - who may hold the balance in next year's elections - may squirm even more.

These include Sen. Susan Collins (R-Maine), Sen. Cory Gardner (R-Colo.), Sen. Martha McSally (R-Ariz.), Sen. Joni Ernst (R Iowa) and Sen. Thom Tillis (R-N.C.). All are either slight favorites or in toss-up races against likely formidable opponents.

Voters, according to politicians and polls, care more about health care, the economy, immigration and education than impeachment. But a pitched congressional battle over removing Trump will affect marginal races, probably energizing voters on both sides.

Any possible Senate votes wouldn't occur for at least ten weeks. Ten weeks ago, little was known about the scandal, in which the president pressured the Ukrainians to dig up dirt on former Vice President Joe Biden while holding up much-needed military assistance.

Senate Republicans have to be worried what else may come out in the weeks and months ahead; court tests may be settled that would require turning over more information - and perhaps even the testimony of administration witnesses in the face of White House stonewalling. Static analysis is perilous in this saga.

Polls show a pronounced partisan split on impeachment: Democrats overwhelmingly for; Republicans overwhelmingly against - with independents divided.

That's why a vote might cause some angst for maybe 15 percent of the new House Democrats who won Republican-held seats last year and several non-freshmen Democrats.

But any on the fence have a believable argument: Impeachment is like an indictment, and plenty of abuse of power and obstruction of justice particulars have emerged.

That won't avail in the Senate, where Republicans hold a 53 to 47 Republican majority and it takes a two-thirds vote to convict.

If this scenario plays out, it will pressure a few Democratic Senators - but it will mainly affect those handful of Republicans in battleground states, where the public is divided. Three of those states - North Carolina, Iowa and Arizona - voted for Trump, who likely would be on the ballot next year. Democrats say all these states will be in play next year.

If more comes out and Senate Republicans look for a compromise like censure instead of impeachment, that's likely to be opposed by one prominent party leader: Donald J. Trump.

Senior Senate Republicans, Like Tennessee's Lamar Alexander, who's retiring, and Rob Portman of Ohio, not up until 2022, may offer an easier cop-out. They say the president's actions were "inappropriate" and "wrong," but trying to shake down a foreign country to go after your political opponent isn't an impeachable offense. In the House, Portman voted to impeach Bill Clinton for lying about sex. Alexander wasn't in Congress yet.

These office holders know Trump owns the party and his base will punish any Republican who goes off the reservation. A recent illustration: Sen. Mitt Romney (R- Utah) has been one of the more outspoken GOP critics of Trump's behavior; in 2012, Romney and former Sen. Rick Santorum basically tied for first in the Iowa caucuses - in last weekend's Iowa poll, Republicans gave Romney a 36 percent favorability rating. Trump, by contrast, has an 85 percent rating.

Most of the marginal Republican Senate incumbents, keenly aware of the Trump base, have indicated, as of now, they'd vote against an impeachment conviction, while trying to avoid the issue. Ernst struggled over a Trump impeachment-related question at a town hall. Gardner has repeatedly declined to say whether it was proper for Trump to pressure a foreign country to smear his political opponent, but he laments impeachment as a "partisan exercise."

McSally, who literally rushed away from reporters at the Capitol when asked about the issue, knows the dangers of trying to walk a fine line. In the Arizona Senate race last year, she tried to self-identify both with Trump and the late Sen. John McCain, two men of profoundly different values and views who had contempt for one another. She lost. She was appointed to the Senate this year to fill a vacancy.

Collins, facing the toughest race of her career in Maine, may be walking the most delicate line. A recent Boston Globe analysis concluded that other than the president, no politician "is more jammed up by impeachment than Collins."