WASHINGTON — Senate negotiators announced on Sunday that they had struck a bipartisan deal on a narrow set of gun safety measures with sufficient support to move through the evenly divided chamber, a significant step toward ending a yearslong congressional impasse on the issue.
The agreement, put forth by 10 Republicans and 10 Democrats and endorsed by President Biden and top Democrats, includes enhanced background checks to give authorities time to check the juvenile and mental health records of any prospective gun buyer under the age of 21 and a provision that would, for the first time, extend to dating partners a bar on domestic abusers having guns.
It would also provide funding for states to implement so-called red-flag laws that allow authorities to temporarily confiscate guns from people deemed to be dangerous, as well as money for mental health resources and to boost safety and mental health services at schools.
The outline, which has yet to be finalized, falls far short of the sprawling reforms that Mr. Biden, gun control activists and a majority of Democrats have long championed, such as a ban on assault weapons and universal background checks. And it is nowhere near as sweeping as a package of gun measures passed almost along party lines in the House last week, which would bar the sale of semiautomatic weapons to people under the age of 21, ban the sale of large-capacity magazines and implement a federal red-flag law, among other measures.
But it amounts to notable progress, given the deep party divisions over how to address gun violence and repeated failed efforts to approve gun reform on Capitol Hill, where Republicans have thwarted action for years. Democrats hailed the plan, which would also toughen federal laws to stop gun trafficking and ensure that all commercial sellers are doing background checks, as an opportunity to pass the most significant gun safety legislation in decades.
“Today, we are announcing a common-sense, bipartisan proposal to protect America’s children, keep our schools safe and reduce the threat of violence across our country,” the 20 senators, led by Christopher S. Murphy, Democrat of Connecticut, and John Cornyn, Republican of Texas, said in a joint statement. “Families are scared, and it is our duty to come together and get something done that will help restore their sense of safety and security in their communities.”
The backing of 10 Republicans suggested that the plan could scale an obstacle that no other proposal currently under discussion has been able to: drawing the 60 votes necessary to break through a G.O.P. filibuster and survive to see an up-or-down vote on the Senate floor.
Senator Mitch McConnell, the Kentucky Republican and minority leader who has played a central role in stymieing gun safety measures in recent years, praised what he called “headway” in the discussions even as he was noncommittal about whether he would support the package.
“The principles they announced today show the value of dialogue and cooperation,” Mr. McConnell said. “I continue to hope their discussions yield a bipartisan product that makes significant headway on key issues like mental health and school safety, respects the Second Amendment, earns broad support in the Senate and makes a difference for our country.”
Aides cautioned that until the legislation was finalized, it was not certain that each of the components could draw the 60 votes necessary to move forward.
The outline includes a provision to address what is known as the “boyfriend loophole,” which would prohibit dating partners from owning guns if they had been convicted of domestic violence or were subject to a domestic violence restraining order. Currently only domestic abusers who are married to, live with or parent a child with a victim are barred from having a firearm.
Republicans balked at including a provision to address the boyfriend loophole in a reauthorization of the Violence Against Women Act, forcing Democrats to drop it in order to pass that legislation in March.
Mr. Biden urged Congress to pass a bill quickly, saying there were “no excuses for delay.”
“Each day that passes, more children are killed in this country,” he said. “The sooner it comes to my desk, the sooner I can sign it, and the sooner we can use these measures to save lives.”
The rare moment of bipartisan agreement came just under three weeks after a gun massacre at an elementary school in Uvalde, Texas, that killed 19 children and two teachers, and about a month after a racist shooting attack in Buffalo that killed 10 Black people in a supermarket. The back-to-back mass shootings pushed the issue of gun violence to the forefront in Washington, where years’ worth of efforts to enact gun restrictions in the wake of such shootings have failed amid Republican opposition.
The agreement was announced on the sixth anniversary of the mass shooting at Pulse, a gay nightclub in Orlando, Fla., where a gunman killed 49 people in what was then the deadliest shooting in modern American history.
Negotiators must now translate the broad principles of the framework into legislative text, a far more fraught process, and secure enough support in both chambers for the legislation to become law.
Senator Chuck Schumer of New York, the majority leader, pledged to put the agreement up for a vote once the legislation had been completed, calling it “a good first step to ending the persistent inaction to the gun violence epidemic that has plagued our country.”
“We must move swiftly to advance this legislation, because if a single life can be saved, it is worth the effort,” Mr. Schumer said in a statement.
Gun safety activists said they viewed the measures as meaningful progress that they hoped would unlock a new era of bipartisanship on the issue.
“The fact that a group this large is coming together to get it done shows that we’re in a historic moment,” said T. Christian Heyne, the vice president for policy at Brady: United Against Gun Violence. “It feels like a critical initial step for what I hope will be a new era in gun violence prevention.”
Mr. Heyne said that closing the dating partner loophole, in particular, has long been one of his organization’s key priorities. “All of these things individually are meaningful,” Mr. Heyne said. “When you look at them together, it feels pretty significant.”
As pressure has mounted for Congress to act in recent days, roughly a dozen senators — including veterans of failed attempts to reach similar deals — huddled on Zoom, over the phone and in basement offices on Capitol Hill to reach an agreement before the Senate leaves for a scheduled Fourth of July recess.
Party leaders signaled support for the discussions, even as Mr. Schumer warned that he would not allow them to drag on into the summer before he would force votes on gun control measures. Mr. Murphy asked Mr. Schumer to hold off on scheduling votes on more sweeping House-passed gun control legislation that Republicans opposed to give room for the talks, and he repeatedly warned that his party’s top priorities would have to be dropped to secure the necessary G.O.P. backing for any compromise.
Democrats who signed onto Sunday’s statement included Mr. Murphy as well as Senator Kyrsten Sinema of Arizona, Richard Blumenthal of Connecticut, Cory Booker of New Jersey, Chris Coons of Delaware, Martin Heinrich of New Mexico, Mark Kelly of Arizona, Joe Manchin III of West Virginia and Debbie Stabenow of Michigan. They were joined by Angus King, the Maine independent.
The group of Republicans included four senators who are leaving Congress at the end of the year: Roy Blunt of Missouri, Richard Burr of North Carolina, Rob Portman of Ohio and Patrick J. Toomey of Pennsylvania. The remainder were all senators who are not up for re-election this year: Mr. Cornyn as well as Thom Tillis of North Carolina, Bill Cassidy of Louisiana, Susan Collins of Maine, Lindsey Graham of South Carolina and Mitt Romney of Utah.
“I worked closely with my colleagues to find an agreement to protect our communities from violence while also protecting law-abiding Texans’ right to bear arms,” Mr. Cornyn said in a statement on Twitter.
Last week, the House voted nearly along party lines to pass a far more substantial gun-control bill, including raising the age for purchasing semiautomatic weapons and banning magazines that hold more than 15 rounds of ammunition, as well as the federal red-flag law. With all but a handful of Republicans opposed, none of the measures stood any chance of passage in the Senate.
In an indication of the political risks Republicans see in supporting gun control measures, all but one of the five House Republicans who backed that legislation are also leaving Congress this year.
One of them, Representative Chris Jacobs, Republican of New York, abruptly dropped his re-election bid for his suburban Buffalo district after facing backlash for embracing a federal assault weapons ban.
“We really need to work to re-establish some trust, tone down the rhetoric on both sides, so we can really get some productive dialogue and then results,” Mr. Jacobs said on Sunday on CNN’s “State of the Union.”
Some House Democrats, speaking before the deal was formally announced, said they were cautiously optimistic about the new legislative framework.
“I’m disappointed to hear a focus on increased criminalization and juvenile criminalization instead of really having the focus on guns,” Representative Alexandria Ocasio-Cortez, Democrat of New York, said during a separate appearance on “State of the Union.” “But the background checks provision is encouraging.”
Luke Broadwater contributed reporting.