WASHINGTON (AP) — Majority Leader Chuck Schumer vowed Wednesday that the Senate will vote on legislation to protect same-sex marriage "in the coming weeks" as a bipartisan group backing the bill negotiates changes to gain more Republican support.

The vote, expected by the end of the month, comes as Democrats and a small group of Republicans are moving to safeguard same-sex marriage following the Supreme Court decision that overturned Roe v. Wade and the federal right to an abortion. Lawmakers fear the court's ruling, and a concurring opinion from Justice Clarence Thomas, indicate that an earlier high court decision protecting same-sex marriage could come under threat.

"We all want to pass this quickly," Schumer said. "I hope there will be 10 Republicans to support it."

A bipartisan group of senators, led by Democratic Sen. Tammy Baldwin of Wisconsin, is working to round up those ten GOP votes needed to overcome a filibuster and get the legislation through the 50-50 Senate.

"I think the momentum is going in the right direction," Baldwin said after the bipartisan group met on Wednesday.

The Senate push for the historic vote — and the openness by some Republicans to back it in an election year — reflects a seismic shift on the issue since the Supreme Court's 2015 Obergefell v. Hodges decision legalizing gay marriage nationwide. Some 70% of U.S. adults in a Gallup poll released in June 2021 said same-sex unions should be valid under the law.

The bill protecting same-sex marriage cleared the House in a July vote with the support of 47 Republicans – a larger than expected number that gave the measure a boost in the Senate.

To win over more Senate Republicans, negotiators are planning to introduce amendments aimed at addressing concerns from some about "religious liberty" – the rights of religious institutions or religious business owners to oppose same-sex marriage, for example. Supporters say such religious liberty is already enshrined in law, but new language would simply make that clear.

Another proposed tweak to the bill would make clear that a marriage is between two people, an effort to ward off some far-right criticism that the legislation could endorse polygamy.

Baldwin and two of the Republicans supporting the marriage bill, Maine Sen. Susan Collins and North Carolina Sen. Thom Tillis, said Wednesday that the group was drafting the amendments to address the concerns they've heard from their GOP colleagues.

"There's no harm in doing it," Tillis said, even though some Democrats have pointed out that those rights are already protected under law.

Collins said the amendment would "make crystal clear that it does not in any way infringe religious liberties" and allow Republicans to have input on the bill.

"I'm never confident until the roll is called but we're making good progress," Collins said.

The legislation would repeal the Clinton-era Defense of Marriage Act and require states to recognize all marriages that were legal where they were performed. The new Respect for Marriage Act would also protect interracial marriages by requiring states to recognize legal marriages regardless of "sex, race, ethnicity, or national origin."

So far, three Republicans have said they will vote for the legislation and are working with Baldwin and others to pass it: Collins, Tillis and Ohio Sen. Rob Portman. A fourth GOP senator, Alaska Sen. Lisa Murkowski, has supported same-sex marriage in the past. Wisconsin Sen. Ron Johnson, who is up for reelection this year, has said he doesn't see a "reason to oppose it" but has talked on both sides of the issue in recent weeks.

Several other Republican senators have said they are undecided or have declined to comment.

"I don't have anything for you on that at this point," Pennsylvania Sen. Pat Toomey said Wednesday, when asked if he would vote for the bill.

Indicative of the political shift, many of the Republicans who are opposing the bill aren't arguing whether same-sex marriages should be recognized by the government. They say instead that they believe the Supreme Court is unlikely to overturn Obergefell.

"I don't think that's a pressing matter," said Sen. Marco Rubio, R-Fla., who is up for re-election this year. "There's no threat to same-sex marriage in America."

Republican Sen. John Cornyn of Texas said the effort is a "show vote" and Democrats are playing politics.

Baldwin, who is the first openly gay senator and has been working on gay rights issues since she first entered state politics in the 1980s, said she disagrees with that assessment.

"It's not" just politics, Baldwin said. "It's very real for a whole lot of people."

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Associated Press writers Farnoush Amiri, Nomaan Merchant and Lisa Mascaro contributed to this report.