Tom Davis, a former Virginia congressman and chair of the National Republican Congressional Committee, argued that while the alternative to the ACA faces resistance in polls, opposing it would have been a greater risk for House Republicans than supporting it. That is because he believes failure would have depressed the Republican base. Like other GOP strategists, Davis views that as a greater risk than alienating swing voters, who polls have shown dislike both the original GOP bill that failed earlier this spring and the changes that were made to revive it.

“I think they have to pass it, because a dispirited base going into the midterms [is dangerous],” he said. “The Democratic base is going to be spiked no matter what. So they have to do this.”

Davis, now president of federal affairs for the consulting company Deloitte said he believes Democrats face a demographic impasse on the legislation. On the one hand, in the white-collar, “higher-income suburban districts” where Trump is unpopular—and where Republicans appear most vulnerable for 2018—“you’re not taking their stuff away, they are not the people who are getting punished,” he argued. On the other, the GOP advantage, largely on cultural issues and Trump-like nationalism, is too entrenched to overturn in the blue-collar and rural districts likely to face greater material consequences from the repeal, he said.

But Charlie Kelly, executive director of House Majority PAC, a political-action committee that supports Democratic House candidates, said the health-care legislation’s tangible economic impact had the potential to cut through the GOP’s cultural advantage in the blue-collar and nonurban districts that have been trending toward Republicans since 2010.

“This is very much a kitchen-table thing,” Kelly said. “It’s something that is very easy to understand, and from a connection standpoint it’s not hard for people to see they just took away 24 million Americans’ health care. You can’t explain that. And all these things with charging seniors and folks over 50 more [for premiums], that just doesn’t make sense. Who is on your side is a fundamental question.” In economically struggling blue-collar communities, Kelly added, “They took a chance on Trump and this is a shock.”

Polls found the initial Republican legislation faced preponderant public opposition: A late March Quinnipiac University survey found that fewer than one in five adults supported it, while 56 percent opposed it. Opposition spiked past 60 percent among older adults ages 50 to 64, a largely white and Republican-leaning constituency. An ABC/Washington Post survey likewise found that 70 percent of all adults—and three-fourths of those 50 and older—opposed ending the ACA’s nationwide guarantee of affordable coverage for people with preexisting conditions. The House legislation allows states to opt out of those protections.

Despite the warning signs in public opinion, the bill drew broad support from Republicans in every category of electorally conflicted district. Eight House Republicans hold seats that voted Democratic in each of the past three presidential elections, per TargetSmart’s analysis. They split evenly on the health-care vote, with four opposing and four supporting the bill. The supporters were Jeff Denham and David Valadao of California, Carlos Curbelo of Florida, and Erik Paulsen of Minnesota. Clinton carried the Valadao and Curbelo districts by more than 15 percentage points, the Paulsen district by 9, and the Denham district more narrowly by three. (The opponents were: Mike Coffman of Colorado, John Katko of New York, David Reichert of Washington, and Ileana Ros-Lehtinen of Florida.)