Rep. Tom Cotton (R-Ark.) during a Fayetteville High School football game in October 2014, less than a week before his election to the Senate. (Justin Sullivan/Getty Images)

In one corner of a packed and muggy hotel ballroom sat a man wearing a black “Team Trump” T-shirt. But in another was a sign urging: “TRUMPCARE GO (BACK) TO SIBERIA.” At the front stood Tom Cotton, an ambitious Republican senator plunged into the crossfire on health care by the election of Donald Trump.

“Senator Cotton, do you support repealing the Affordable Care Act so that 300,000 Arkansas citizens will lose their health care?” a woman asked him at a town hall meeting here this year. She was referring to the state’s unique Medicaid expansion initiative created under the ACA, in which more than 300,000 people have enrolled.

“I would disagree with the premise of your question, that if we repeal the Affordable Care Act, that that’s going to happen,” Cotton said, drawing loud boos.

Republicans made their biggest stride yet toward fulfilling their years-long pledge to undo the ACA, commonly known as Obamacare, when the House passed a controversial overhaul bill Thursday. The measure now heads to the Senate.

(Jenny Starrs/The Washington Post)

There, Cotton and other Republican senators will have to grapple with forces pulling them in different directions: their own promises to repeal and replace the 2010 Affordable Care Act; the reality that many of their home states are filled with constituents who have benefited from Obamacare; and the perilous challenge of negotiating with Trump, who has shown a willingness to lash out at unruly Republican lawmakers.

How they navigate those ­pressures will largely shape what, if any, bill comes out of the upper chamber of Congress.

Just a few months ago, Cotton appeared to be poised for his own presidential run. He was in Iowa four weeks before November’s election — a time when many Republicans were losing hope that Trump could win and were looking ahead to 2020.

Then Trump won. And suddenly, ascendant Republicans such as Cotton had to confront a difficult question: What now?

That question is no less challenging as the health-care debate moves to the Senate amid deepening political divides across the country triggered by Trump’s presidency.

Sen. Tom Cotton (R-Ark.) speaks during a television interview on Capitol Hill last month. (J. Scott Applewhite/Associated Press)

Like many of his Senate Republican colleagues, Cotton, 39, was not impressed by the health-care bill passed by the House. “We’re going to write our own bill,” he said, echoing Senate GOP leaders.

Cotton belongs to a health-care working group of Senate Republicans that includes lawmakers from different parts of the ideological spectrum. The group met Thursday to plot its next steps.

On most issues, the lanky Cotton, a rising star in the party, has emerged as one of President Trump’s staunchest supporters, aligning in both tone and substance with the enthusiastic conservative base that helped elect the president. However, on health care, he has not marched in lockstep with the president, whose election made real the possibility of dismantling the ACA for the first time since it was signed into law.

Then-Rep. Tom Cotton (R-Ark.) looks for questions in a crowd of supporters at a Republican headquarters in April 2014, the year he went on to defeat incumbent Sen. Mark Pryor. (Stephen B. Thornton/For The Washington Post)

Even as Cotton reiterated his opposition to the ACA at that town hall meeting in April, he was determined to distance himself from the House bill that was introduced in March and championed by Trump. To the woman who voiced concerns about people losing coverage, he said: “Part of my problems with the bill that was introduced in the Congress last month . . . is that it could have had that result, and it was moving too fast. I didn’t think it got it right, that it was better to slow down, and get it right rather than get it fast.”

When Cotton said, “I do support repealing Obamacare,” he set off a mix of cheers and boos. He added: “I have no doubt that some Arkansans benefited from Obamacare. Many more were hurt by Obamacare.”

The ACA’s dramatic impact in Cotton’s home state — which leans conservative and voted heavily for Trump — has put the first-term senator in an awkward position. From 2013 to 2016, the uninsured rate in Arkansas dropped more than 12 percentage points — more dramatically than in any state except Kentucky, according to a Gallup survey.

Arkansas implemented a variation of Medicaid expansion that was offered under the ACA, giving some people federal aid to purchase private insurance. Cotton does not hold a position for or against the program, his spokeswoman Caroline Rabbitt confirmed. “Going forward he wants to ensure the governor has the flexibility he needs to help Arkansans adapt to any changes to Medicaid,” she added.

(Youtube/Springdale Public Schools)

Still, Cotton broadly opposes the Medicaid expansion that was created under the ACA, as many conservatives do. That leaves Cotton walking a tightrope, which has drawn some skepticism at home that he is playing politics.

“There’s kind of a joke among liberals here that he was created in a lab, as we always say, because he’s this conservative everyman,” said Camille Richoux, 26, of Little Rock, a liberal organizer who attended Cotton’s town hall.

Other Cotton constituents have concluded that Obamacare is not working and want to see lawmakers come up with a functional long-term alternative.

“Slow down, look at this thing and get it right. It’s not going to be perfect,” said David Jones, 70, of Conway, Ark., who wore a Trump hat.

As he spoke in an interview after the town hall, an argument broke out a few feet away, underscoring the raw tensions at the meeting.

“Why did you even bother coming?” a woman asked another.

“Don’t ask me why I came here,” the second woman shot back angrily. “I vote. I have as much right to be here as you do!”

Then-Rep. Tom Cotton greets supporters during a campaign rally in November 2014 in Little Rock shortly before he defeated incumbent Sen. Mark Pryor (D). (Justin Sullivan/Getty Images)

For Senate Republican leaders, coming up with a health bill that has broad appeal will be difficult.

Republican senators in other states that expanded Medicaid have openly worried about the impact the language in the House bill would have on people who obtained coverage through the initiative.

“I think we’re going to have to really look at it closely. I couldn’t commit to supporting it right now,” said Sen. Shelley Moore Capito (R-W.Va.), one such lawmaker.

At the other end of the spectrum are conservative senators such as Rand Paul (R-Ky.) who want to see a more forceful repeal than many of his GOP colleagues. “I’m still open-minded. I do want to vote for a repeal bill,” said Paul, sounding a noncommittal note.

As the House shaped its bill in the spring, Cotton urged caution in the pace at which it was proceeding, but he did not advocate restraint in shredding some directives in the ACA. In effect, it was a simultaneous nod to conservatives on policy and centrists on timing.

“The bill does not address most of the Obamacare regulations that help drive up the cost of insurance in the first place,” Cotton said during a March interview in his Senate office.

On many other matters, Cotton has advocated for Trump. During his town hall, he was asked about Trump’s decision not to release his tax returns, a controversial position that has drawn increasing criticism, even from Republicans.

“As far as I’m aware, the president says he’s still under audit,” said the senator, excusing Trump.

“Awwww!” “Boooo!” exclaimed the crowd in one of their most vocal outbursts.

Cotton, an Army veteran of the wars in Iraq and Afghanistan who has built a reputation around his hawkish national security views, also backed Trump’s foreign policy approach. He said the president made the “right call” with his decision to strike a Syrian air base last month.

But many attendees saw the president’s overall strategy abroad in an unfavorable light.

“Lock him up!” some chanted as Cotton defended the president’s foreign policy and ticked through the list of world leaders Trump has met with. They were putting a twist on “Lock her up!” — a popular anti-Hillary Clinton chant at Trump campaign rallies. Others tried to drown them out with “U.S.A.!”

Photographed by hoards of media, Senate Minority Leader Mitch McConnell (R-Ky.), soon to be majority leader, stands with newly elected Republican senators Shelley Moore Capito (W.Va.), James Lankford (Okla.), Tom Cotton (Ark.), Thom Tillis (N.C.) and Steve Daines (Mont.) on Capitol Hill in November 2014. (Melina Mara/The Washington Post)

“We have serious division. I mean, those divisions were on display last year during the campaign. They remain on display,” Cotton said at the town hall. He sought to add a bipartisan note: “That doesn’t mean we don’t work together on a case-by-case basis.”

But the effort to reshape the country’s health-care system is not fostering much bipartisanship. Not a single Democrat voted for the House bill, and no Democrats are expected to support the effort in the Senate.

GOP leaders are not even banking on getting all 52 Republican senators to vote for a health-care bill, given their disagreements, differing local considerations and discordant political motivations.

“We’d love to get, you know, 52 votes on whatever it is that ultimately emerges from the Senate,” said Sen. John Thune (S.D.), the third-ranking Republican senator. “But we know we have to get 50 plus Vice President Pence.”

Sen. Tom Cotton (R-Ark.) makes his way to a GOP policy luncheon on Capitol Hill in Washington in March. (J. Scott Applewhite/Associated Press)