WASHINGTON — The Senate pushed a bipartisan gun violence bill to the brink of passage Thursday as it voted to halt a Republican filibuster against the measure, clearing the way for Congress’s most far-reaching response in decades to the nation’s run of mass shootings.

After years of GOP procedural delays that derailed Democratic efforts to curb firearms, Democrats and some Republicans decided that congressional inaction was untenable following last month’s rampages in New York and Texas. It took nearly a month of closed-door talks, but a group of senators from both parties emerged with an 80-page compromise.

The measure would toughen background checks for the youngest gun buyers, keep firearms from more domestic violence offenders, and help states implement “red flag” laws that make it easier for authorities to take weapons from people adjudged dangerous. It would also fund local programs for school safety, mental health, and violence prevention.

Thursday’s roll call ending the blockade by conservative GOP senators was 65-34, five more than the 60-vote threshold needed. Final passage of the $13 billion measure was expected by week’s end with a House vote to follow, though timing was uncertain.

Fifteen Republicans joined all 50 Democrats, including their two allied independents, in voting to move ahead on the bill.

But highlighting the risks Republicans face by defying the party’s pro-gun voters and the National Rifle Association, Senators Lisa Murkowski, Republican of Alaska, and Todd Young, Republican of Indiana, were the only two standing for re-election this fall. Of the rest, four are retiring and eight don’t face voters until 2026.

The election-year package fell far short of the more robust gun restrictions Democrats have sought for years, including bans on the assault-type weapons and high-capacity ammunition magazines used at Buffalo, New York, and Uvalde, Texas. Yet the accord let leaders of both parties declare victory and demonstrate to voters that they know how to compromise and make government work, while also leaving room for each side to appeal to its core supporters.

“This is not a cure-all for all the ways gun violence affects our nation,”  Senator Schumer, Democrat of New York, said. His party has made gun restrictions a goal for years. Yet, “it is a long overdue step in the right direction. It’s significant, it’s going to save lives.”

“The American people want their constitutional rights protected and their kids to be safe in school,”  Senator McConnell, Republican of Kentucky, said in a nod to the Second Amendment right to bear arms that drives many conservative voters. “They want both of those things at once, and that is just what the bill before the Senate will have accomplished.”

Yet while the Senate measure was a clear breakthrough, the outlook for continued congressional movement on gun curbs is dim. Only about one-third of the Senate’s 50 GOP senators backed the measure and solid Republican opposition in the House is certain, and both chambers — now narrowly controlled by Democrats — could well be run by the GOP after November’s midterm elections.

Underscoring the enduring potency of conservative clout, Thursday’s vote occurred minutes after the right-leaning Supreme Court issued a decision expanding the right of Americans to carry arms in public. Their ruling struck down a New York law that has required people to prove a need for carrying a weapon before they get a license to do so.

The White House voiced President Biden’s support for the legislation, citing his visits to Buffalo and Uvalde after the shootings.

“The family members delivered a simple message, which the President then relayed to the American people: do something,” a statement said. It said that while Biden wants tougher restrictions, the bill “would make meaningful progress to combat gun violence.”

Senate action came one month after a gunman killed 19 students and two teachers at Uvalde. Just 10 days before that, a white man accused of being motivated by racism killed 10 black grocery store shoppers at Buffalo. Both shooters were 18 years old, a youthful profile shared by many mass shooters.

The talks were led by Senators Murphy, Democrat of Connecticut, Sinema, Democrat of Arizona, Cornyn, Republican ofTexas, and Tillis, Republican of North Carolina. Mr. Murphy represented Newtown, Connecticut, when an assailant killed 20 students and six staffers at Sandy Hook Elementary School in 2012, while Mr. Cornyn has been involved in past gun talks following mass shootings in his state and is close to Mr. McConnell.

The bill would make the local juvenile records of people 18 to 20 years old available during required federal background checks when they attempt to buy guns. Those examinations, currently limited to three days, would last up to a maximum of 10 days to give federal and local officials time to search records.

People convicted of domestic abuse who are current or former romantic partners of the victim would be prohibited from acquiring firearms, closing the so-called boyfriend loophole.

That ban currently only applies to people married to, living with or who’ve had children with the victim. The compromise bill would extend that to those considered to have had “a continuing serious relationship.”

There would be money to help states enforce “red flag” laws and, for other states without them, for violence prevention programs. Nineteen states and the District of Columbia have “red flag” laws and Mr. Cornyn — whose state does not — demanded the inclusion of all states during the negotiations.

The measure expands the use of background checks by rewriting the definition of the federally licensed gun dealers required to conduct them. Penalties for gun trafficking are strengthened, billions of dollars are provided for behavioral health clinics and school mental health programs and there’s money for school safety initiatives, though not for personnel to use a “dangerous weapon.”