President Donald Trump’s hurdle to getting a health care bill passed in the House right now is a bloc of relatively moderate Republicans — and in his desperate bid to get a plan, any plan, moving through Congress, he is leaving those lawmakers with no good options.

Conservatives are already attacking them for blocking the long-sought goal of (partially) repealing Obamacare, raising the specter of primary challenges. But if they vote for the unpopular House bill, they could be vulnerable to Democratic opponents in 2018, putting the GOP’s House majority at risk.

The latest version of the American Health Care Act, which House leaders and the White House are pushing to bring up for a vote this week, includes an amendment that lets states opt out of some of Obamacare’s core insurance rules. The amendment was enough to win over the conservative Freedom Caucus, which had opposed earlier versions of the bill.

That puts the magnifying glass squarely on the Tuesday Group, a group of 50 or so comparatively centrist House Republicans. Many of them were already uneasy with the AHCA because it would lead to an estimated 24 million people being uninsured, and deeply cut the Medicaid program.

And the bill became even more conservative after the latest changes, which allow states to waive some of Obamacare’s protections for people with preexisting medical conditions. Those are among the law’s most popular provisions.

Based on public whip counts, the moderates make up the bulk of the remaining opposition to the bill. Now that the Freedom Caucus has dropped its resistance, those lawmakers are under increasing pressure to come on board.

“The problem was the Freedom Caucus, and now who’s got the hot potato? The Tuesday Group. Again. Again,” Congress member Chris Collins, a New York Republican who does support the bill, said last week. “Again and again and again, the tough votes come back to the Tuesday Group.”

Trump’s desire to force a health care bill through the House, and his willingness to move the bill to the right to appease the Freedom Caucus in his pursuit, has left these Republicans with an impossible choice.

The Tuesday Group is essential to the GOP’s control of the House

Control of the House is decided by swing districts, the ones that lean only narrowly toward Democrats or Republicans, and the GOP’s grip on power is more tenuous than the numbers — 238 to 193 — might lead you to believe. Twenty-three House Republicans represent districts that voted for Hillary Clinton in 2016. If Democrats win those districts, they’ll almost certain to regain control of the House.

Experienced House Republicans are well aware of that risk. The Democratic congressional committee’s list of Republican incumbents that it’s targeting next year matches nearly name for name with the “No” or undecided votes on the AHCA.

“I do think, sometimes, some of our colleagues forget the Tuesday Group is the group that holds the toughest seats for us,” Congress member Tom Cole of Oklahoma, who is close to leadership and once ran the House Republican political committee, said last week. “They really are the difference between us being in the majority and the minority. So what they have to say is extremely important for everybody to listen to, because that’s where our losses will tend to come in a midterm.”

A lot can happen between then and now, of course. But the president’s party usually loses seats in off-year elections — and we have a very recent example of a party seeing historic losses after a contentious health care debate.

Democrats lost 63 seats in the 2010 midterms. Not all of that can be attributed to Obamacare, but the newly minted health care law played a central role in Republican campaigns against Democratic incumbents.

Voting against the Affordable Care Act couldn’t even inoculate some more centrist Democrats — Michael Arcuri of New York and Zack Space of Ohio among them — from losing their seats that year.

“It became a bigger tide,” Brendan Daly, who was an aide to then-House Speaker Nancy Pelosi during the Obamacare debate, told me, “Health care was one big driver.”

Now Trump, his approval rating already historically low for a presidency so young, is pushing the House to pass a bill that only 17 percent of Americans support.

Voting against the AHCA puts them at risk of primary challenges from the right

But voting against the Republican bill, and against the president’s wishes, isn’t a foolproof plan either. Outside conservative groups are already attacking the Tuesday Group for wanting to keep Obamacare — a cardinal sin for much of the Republican base, which still wants Congress to repeal the law. They’ve even gone on the air with campaign-style ads to pressure moderates to back the health care bill.

And while Trump is pretty unpopular with the American public, he maintains solid support among Republicans: 86 percent, according to the latest Gallup poll. Defying Trump could be risky if conservatives are so mobilized by a “No” vote on the AHCA that they seek out a more conservative primary challenger to run against the moderate holdouts.

“He's still popular with a strong majority of those who voted for him. That's what the moderates have to factor in,” a Republican health care lobbyist told me.

“You can't win a general if you lose in a primary,” the lobbyist said, “so the moderates are going to have to make individual political calculations on the likelihood of getting primaried, and by whom.”

Some of the “No” votes on the AHCA already have primary opponents in waiting. Congress member Mark Amodei of Nevada is being challenged by Sharron Angle, a far-right Republican who shocked the world when she won the GOP nomination for US Senate in 2010 — though she went on to lose.

For now, Amodei doesn’t seem fazed. His opposition to the AHCA’s deep Medicaid cuts outweigh concerns about an opponent running to his right.

.@MarkAmodeiNV2 @SharronAngle "If I were really concerned about that I’d probably be trying to find a way to kick all these people off Medicaid instead of going on MSNBC" — Simone Pathe (@sfpathe) April 27, 2017

But his predicament still illustrates the way that the White House’s insistence on forcing the AHCA through could put the holdouts in a political bind. Angle is basing her campaign on the need to give Trump a more conservative Congress that will pass his agenda.

House leaders are taking a similar tack: The real risk for lawmakers is not repealing Obamacare like they promised.

“I think people’s seats are at risk if we don’t do what we said we’d do,” Speaker Paul Ryan said last week. “We promised that we would do this. If you violate your promise, if you commit the sin of hypocrisy in politics, that’s the greater risk.”

Voting for the AHCA puts them at risk of losing to Democrats in 2018

For some of the holdouts, a primary challenge might sound far-fetched. Rep. Charlie Dent of Pennsylvania, one of the moderates most stridently opposed to the AHCA, has held his seat in the Allentown area for 12 years now. It’s tough to overcome the inertia of political incumbency, and these are districts that elected moderate Republicans in the first place.

But as Rep. Cole observed, when it comes to the general election, these Tuesday Group lawmakers are unquestionably the most at risk. If the Democrats end up taking the House, the wave will start in the swing districts moderates represent.

“When they tell me something is unpalatable politically, I listen because my gavel depends on them coming back,” Cole said. “I think everybody in our conference ought to realize that.”

Democrats are already running campaign ads against the swing district incumbents over the health care bill.

Early returns on the special House elections this year — an admittedly imperfect barometer, but a data point nonetheless — can’t be encouraging for the vulnerable lawmakers. Two solid Republican districts in Georgia and Kansas swung 20 points or so toward Democrats from their last congressional election.

And the more Democrats like their chances, the stronger the candidates they can recruit to challenge these swing-district incumbents.

Congress member Tom MacArthur, a New Jersey Republican and member of the Tuesday Group, negotiated the new amendment to the AHCA that won over the Freedom Caucus. He supports the bill and is already one of the Democratic targets. Last week, a former Obama administration official and veteran announced he would explore a run against MacArthur over his role in shaping the GOP health care plan.

Yesterday Rep Tom MacArthur became TrumpCare 2.0 author. Today I’m exploring run against him Congress NJ03. Join me https://t.co/UO5MBcFa1D pic.twitter.com/xvfJPz1H5b — Andy Kim (@AndyKimNJ) April 27, 2017

The Republican holdouts are well aware of all this. That’s why they’re balking at legislation that will lead to an estimated 24 million more people being uninsured — at least.

The latest version of the AHCA hasn’t actually been evaluated yet by the Congressional Budget Office yet, and it probably won’t be before the House votes. But if the House passed the bill, you can bet Democrats will ask the CBO for a score, which could come back with even deeper coverage losses and more ammunition for Democratic ads against the vulnerable Republicans.

So these lawmakers are being asked to take a tough vote, without a full picture of what the bill would do — and without knowing how the Senate would change the bill and whether their conservative counterparts in the Freedom Caucus would agree to any such compromise with the Senate.

A tough vote, then, on a bill that’s moved to the right and without any guarantees of getting an actual law out of it. All because Trump refuses to accept failure on health care.

It’s clearly weighing on them.

“The business model around here is to load the bill up, make it as conservative as possible, send it to the Senate, and then have the senate clean it up and send it back,” Dent told reporters last week. “Then the very people who were placated on the first launch won’t be there anymore on the final.”

“That dog isn’t hunting anymore,” he said.