The US Senate has easily approved a bipartisan gun violence bill that seemed unthinkable just a month ago, clearing the way for final congressional approval of what will be lawmakers’ most far-reaching response in decades to 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 after last month’s rampages in New York and Texas. It took weeks of closed-door talks but a group of senators from both parties emerged on Thursday with a compromise embodying incremental but impactful movement to curb bloodshed that has come to regularly shock – yet no longer surprise – the nation.

The $13bn measure would toughen background checks for the youngest gun buyers, keep firearms from more domestic violence offenders, and help states put in place red-flag laws that make it easier for authorities to take weapons from people judged to be dangerous. It would also fund local programs for school safety, mental health and violence prevention.

The election-year package fell far short of more robust gun restrictions Democrats have sought for years, including bans on the assault-type weapons and high-capacity ammunition magazines used in the slayings in 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,” said the Senate majority leader, Chuck Schumer, whose Democratic party has made gun reform a goal for decades. “But it is a long overdue step in the right direction. Passing this gun safety bill is truly significant, and it’s going to save lives.”

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

The day proved bittersweet for advocates of curtailing gun violence. Underscoring the enduring potency of conservative clout, the right-leaning supreme court issued a decision expanding the right of Americans to carry arms in public. The justices 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 vote on final passage was 65-33.

Hours earlier, senators voted 65-34 to end a filibuster by conservative GOP senators. That was five more than the 60-vote threshold needed. The House planned to vote on the measure on Friday and approval seemed certain.

On that vote, 15 Senate Republicans joined all 50 Democrats, including their two allied independents, in voting to move ahead on the legislation.

Yet that vote highlighted the risks Republicans face by defying the party’s pro-gun voters and firearms groups like the National Rifle Association. Senators Lisa Murkowski of Alaska and Todd Young of Indiana were the only two of the 15 up for reelection this fall. Of the rest, four are retiring and eight don’t face voters until 2026.

Tellingly, GOP senators voting “no” included potential 2024 presidential contenders like Tom Cotton of Arkansas, Ted Cruz of Texas, Josh Hawley of Missouri and Tim Scott of South Carolina. Some of the party’s most conservative members voted “no” as well, including Rand Paul of Kentucky and Mike Lee of Utah.

While the Senate measure was a clear breakthrough, the outlook for continued congressional movement on gun curbs is dim.

Less than a third of the 50 GOP senators backed the measure and solid Republican opposition is certain in the House. Top House Republicans urged a “no” vote in an email from the No 2 GOP leader, representative Steve Scalise of Louisiana, that called the bill “an effort to slowly chip away at law-abiding citizens’ second amendment rights”.

Both chambers – now narrowly controlled by Democrats – could be run by the GOP after November’s midterm elections.

The president, Joe Biden, said in a statement that Uvalde residents told him when he visited that Washington had to act.

“Our kids in schools and our communities will be safer because of this legislation. I call on Congress to finish the job and get this bill to my desk,” Biden said.

Senate action came one month after a gunman killed 19 students and two teachers in Uvalde. Just days before that, a white man was accused of being motivated by racism as he killed 10 Black grocery shoppers in Buffalo. Both shooters were 18 years old, a youthful profile shared by many mass shooters, and the close timing of the two slaughters and victims with whom many could identify stirred a demand by voters for action, lawmakers of both parties said.

The talks were led by Democratic senators Chris Murphy and Kyrsten Sinema and Republicans John Cornyn and Thom Tillis. Murphy represented Newtown, Connecticut, when an assailant killed 20 students and six staffers at Sandy Hook elementary school in 2012, while Cornyn has been involved in past gun talks after mass shootings in his state and is close to McConnell.

Murphy said the measure would save thousands of lives and was a chance to “prove to a weary American public that democracy is not so broken that it is unable to rise to the moment”.

“I don’t believe in doing nothing in the face of what we saw in Uvalde” and elsewhere, Cornyn said.

The bill would make the local juvenile records of people aged 18 to 20 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 have 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 such laws.

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 is money for school safety initiatives, though not for personnel to use a “dangerous weapon”.