These are the 15 Republican senators who voted for the bipartisan gun bill.

The Senate passed a bipartisan measure aimed at gun safety, breaking a yearslong stalemate over federal legislation to address rampant violence. Fifteen Republican senators broke with their party to vote in favor of the bill, which passed 65 to 33. Only two of the Republicans who supported the bill are facing re-election this year, indicating how difficult it could be to advance similar compromises in the future.

Mitch McConnell of Kentucky, the Senate minority leader, expressed public support for the bill, calling it “a common sense package of popular steps that will help make these horrifying incidents less likely while fully upholding the Second Amendment rights of law-abiding citizens.” He has an A+ rating from the National Rifle Association, and his backing for the measure was seen as key to its passage. The other Republicans who supported the measure were:

• Roy Blunt of Missouri, chairman of the Senate Republican Policy Committee, is not as moderate as other Republican senators who voted yes, and previously was leaning no on the bill. Mr. Blunt has said that he would not seek re-election this year. He has an A rating from the National Rifle Association.

• Richard Burr of North Carolina signed onto the bipartisan gun framework released in early June. He is retiring from Congress at the end of the year and has an A+ rating from the N.R.A.

• Shelley Moore Capito of West Virginia was one of the surprise Republicans voting yes who previously deflected when asked where she stood on a gun control bill. Her home-state Democratic colleague, Joe Manchin, was an early and vocal supporter of a narrower bill during deliberations. Capito has an A rating from the N.R.A.

• Bill Cassidy of Louisiana worked on the bill’s mental health component. He isn’t up for election until 2026 and has an A rating from the N.R.A.

• Susan Collins of Maine was active in the negotiations over provisions for firearm trafficking, having introduced the Stop Illegal Trafficking in Firearms Act last year. “There are mixed views back home, but by and large, the reaction has been positive because people realize that we’re not hurting law-abiding gun owners,” she said during discussions. She has a B rating from the N.R.A.

• John Cornyn of Texas is a senior member of the Judiciary Committee who attempted to negotiate for expanded background checks last year and was booed at his state’s party convention this past weekend. He was picked by McConnell as a leader for the deliberations over the bill framework as a Republican in a room of centrists who could make or break the bill. He has an A+ rating from the N.R.A.

• Joni Ernst of Iowa serves on Mr. McConnell’s leadership team as vice chairwoman of the Senate Republican Conference. Before Wednesday’s initial vote, Ms. Ernst’s phone was flooded with calls from constituents hoping to sway her to vote for the bill. She has an A rating from the N.R.A.

• Lindsey Graham of South Carolina co-sponsored a restraining order bill in 2018 with Senator Richard Blumenthal, a Connecticut Democrat, to take away firearms from people who might pose a risk. He has an A rating from the N.R.A.

• Lisa Murkowski of Alaska is up for re-election in November as a moderate and has been rewarded by her constituency for her independent streak. “If what we’re doing is making things safer, without taking away people’s Second Amendment rights, I think maybe we’ve knit this just the way it needed to be,” she said. Ms. Murkowski has an A rating from the N.R.A.

• Robert Portman of Ohio is one of the 10 Republican senators who endorsed the bill framework in early June. He will retire this year and has an A rating from the N.R.A.

• Mitt Romney of Utah, along with Ms. Collins and Ms. Murkowski, is known as one of the Republican swing votes in the Senate. He signed the bill framework in June and has an A rating from the N.R.A.

• Thom Tillis of North Carolina was a leader in the negotiations alongside Mr. Cornyn and Chris Murphy, a Democrat from Connecticut. Mr. Tillis has an A rating from the N.R.A.

• Pat Toomey of Pennsylvania is one of two Republicans who supported expanded background check legislation in 2013. He is retiring from the Senate this year and has a C rating from the N.R.A.

• Todd Young of Indiana was a more surprising Republican yes vote. On Wednesday, he suggested that he was still examining the details of the bill. “We didn’t have a whole lot of time to review the text and solicit, from various stakeholders and experts, thoughts on it. I remain open to supporting it. I also remain open to not supporting it,” he said. He has an A+ rating from the N.R.A.