His decision to get involved was emblematic of a Republican Party that’s divided over how much to edge away from hardline positions on social issues as it tries to rebuild credibility with swing voters after a disappointing midterm performance. As much as some Republicans hope to counterbalance the chaos of the Trump years and a conservative Supreme Court majority’s reversal of Roe v. Wade, same-sex marriage still plainly splits the GOP: Tillis, Collins, and Portman joined just nine other Republican senators to ultimately support the bill.

Tillis said that it shouldn’t have shocked people to see him so out front on same-sex marriage way back in July: “That’s probably the libertarian side of me.” Tweaking the bill to allow more religious freedom exemptions, he added, helped Republicans deliver a stronger message to voters “that this is not about an extreme liberal, progressive end that would destroy religious freedom in this country.”

“This was about settling something that is on the minds of millions of people and their families,” Tillis said. “And I thought it was worth doing.”

Some political evolutions develop over decades, then accelerate in an instant. That’s how it happened for Democrats, who were divided over same-sex marriage during former President Barack Obama’s first term until then-Vice President Joe Biden announced his support 10 years ago. Obama followed, and the rest of the party was not far behind.

It’s been a slower trickle for Republicans. Portman, Collins and Sen. Lisa Murkowski (R-Alaska) were on a fairly lonely island in favor of same-sex marriage for years. And as he left Congress in 2016, former Rep. Richard Hanna (R-N.Y.) — another early supporter — castigated his party for being too intolerant on the issue.

This summer, 47 House Republicans’ surprising support for the same-sex marriage bill spurred a sustained push from Tillis, Portman and Collins to take action — a veritable GOP tidal shift. As former Senate Majority Leader Trent Lott (R-Miss.) put it on Tuesday: “Times change. And senators change.”

“I do feel that the young populations are much more accepting of diverse opinions when it comes to same-sex marriage. And I think this is something that in years to come is not going to be an issue. It shouldn’t be,” said Sen. Joni Ernst (R-Iowa), whose state was one of the first in the country to legalize same-sex marriage.

Ernst and Sen. Shelley Moore Capito (R-W.Va.) are the highest-ranking Senate Republicans to support the legislation as they prepare to ascend to Nos. 4 and 5 in GOP leadership next year. Two House Republican leaders, Elise Stefanik of New York and Tom Emmer of Minnesota, supported a previous version of the legislation. The Senate’s amended bill now goes back to the House, where it’s assured of final passage but the ultimate number of GOP supporters is in flux.

The bill’s Senate GOP backers are a motley group, including moderates like Collins and Murkowski but also Sen. Cynthia Lummis (R-Wyo.), who objected to President Joe Biden’s election certification and routinely votes against bipartisan bills. Retiring Sens. Richard Burr (R-N.C.) and Roy Blunt (R-Mo.) backed the effort, but fellow retiring Sens. Pat Toomey (R-Pa.) and Richard Shelby (R-Ala.) rejected it. Dealmaking Sen. Mitt Romney (R-Utah) joined Tillis, as did Dan Sullivan (R-Alaska).

Senate Majority Leader Chuck Schumer and the bipartisan band of five supporters decided in September to delay a floor vote until after the election; Baldwin and Sinema did not want to risk failure when they knew they could win after the midterms. By mid-November, recently re-elected Sen. Todd Young (R-Ind.) was on board, too.

The square-jawed Marine veteran said he had to do his homework before he came around to the legislation: “I’m a skeptical person.” But he also saw an opportunity to both protect same-sex marriage rights if the Supreme Court ever revisited its 2015 Obergefell decision and simultaneously ensure that every state “would not be required to sanctify same-sex marriages in the future.”

“We’re all doing the best we can to get it right. And I have high confidence that I’ve gotten it right,” Young said.

LGBTQ advocates chafe at the fact that the bill does not truly codify a national right to same-sex marriage, instead repealing the Defense of Marriage Act and requiring all states to recognize marriages performed in other states should the high court reverse its earlier ruling. Supportive Republicans may not have gone further than they did, and the bill only squeaked by Tuesday, 61-36.

Ernst said that she’s evolved on the issue and believes “in traditional marriage, but [I] understand that a lot of our population feels very differently on the issue.” Other Republicans indicated the ultimate legislation achieved a balance in what they could support.

“I think marriage is between one man and one woman. Other people have a different point of view and people have relied upon Obergefell to make their life decisions. I don’t think you go back and unwind marriages that have been performed legally by various states,” Romney said.

Though Republicans privately estimate perhaps 30 or so of their senators want the bill to pass, conservative backlash limited the whip count. Sinema has cut deals on infrastructure and gun safety but said that “the attempts to derail this piece of legislation were probably more focused and robust than any other bills I’ve worked on in the last two years.”

“Real credit needs to be given to the 12 Republicans who are standing with conviction on this piece of legislation to protect religious liberties and to give peace of mind to families all across this country. Because the opposition was very, very strong,” Sinema said.

When explaining her vote on the floor on Tuesday, Lummis alluded to a mountain of criticism back home, saying the days since she first signaled support for the bill “have been fairly brutal self soul-searching. Entirely avoidable, I might add, had I simply chosen to vote no.”

Taking flak for stepping into the bipartisan breach was nothing new for Tillis, even before his summertime work with Sinema and others on gun safety. He’d felt it when he sought to protect then-Special Counsel Robert Mueller during a high-profile probe of former President Donald Trump. After initially opposing Trump’s border wall national emergency, Tillis reversed himself on it as he sought reelection.

So as this Congress ends with another surprising Senate deal on the books, Tillis offered some advice: “Any time you do any bipartisan effort, you’re gonna get a little heat in either direction. You just have to keep moving.”

Marianne LeVine contributed to this report.

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