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 prohibition on domestic abusers having guns.
It would also provide funding for states to enact 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 bolster safety and mental health services at schools.
The outline has yet to be finalized and still faces a perilous path in Congress, given the deep partisan divide on gun measures and the political stakes of the issue. It 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 enact a federal red-flag law, among other steps.
But it amounts to notable progress to begin bridging the considerable gulf between the two political parties on how to address gun violence, which has resulted in a string of failed legislative efforts on Capitol Hill, where Republican opposition has 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 ultimately 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. Senators were still haggling over crucial details, including how much additional time law enforcement would have to review juvenile and mental health records for prospective gun buyers younger than 21.
The outline includes a provision to address what is known as the “boyfriend loophole,” which would prohibit people from owning guns if they had been convicted of domestic violence against a dating partner or were subject to a domestic violence restraining order from one. Currently, only domestic abusers who are married to, living with or the parent of a child with a victim are barred from having a firearm.
Republicans balked in March at including a provision to address the boyfriend loophole in a reauthorization of the Violence Against Women Act — a law aimed at preventing domestic violence, sexual assault and stalking — forcing Democrats to drop it in order to pass that legislation.
Mr. Biden urged Congress to pass a gun safety measure 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 assaults have fallen short amid Republican opposition.
“There’s a different mood in the American public right now,” Mr. Murphy said. “There’s a real panic among families and kids that this country is spinning out of control. That demand presented us with an opportunity.”
Mr. Murphy said his hope was that many more Republicans would end up supporting a bill and that it would help “break this impasse and show the country what’s possible.”
But in an indication of the political risks Republicans see in embracing even modest gun safety measures, none of the 10 who endorsed Sunday’s deal was facing voters this year. The group included four Republican senators who are leaving Congress at the end of the year — Roy Blunt of Missouri, Richard M. Burr of North Carolina, Rob Portman of Ohio and Patrick J. Toomey of Pennsylvania — and five who are not up for re-election for another four years: Mr. Cornyn, Thom Tillis of North Carolina, Bill Cassidy of Louisiana, Susan Collins of Maine and Lindsey Graham of South Carolina. Senator Mitt Romney of Utah, who also embraced the deal, will face voters in 2024.
“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.
Democrats who signed on to Sunday’s statement included Mr. Murphy as well as Senators 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. Mr. Blumenthal and Mr. Kelly are up for re-election in November.
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.
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.
“All of these things individually are meaningful,” Mr. Heyne added. “When you look at them together, it feels pretty significant.”
John Feinblatt, the president of Everytown for Gun Safety, said if the framework announced was enacted into law, “it will be the most significant piece of gun safety legislation to make it through Congress in 26 long and deadly years.”
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. Mr. Murphy asked Mr. Schumer to provide room for the talks by holding off on scheduling votes on more sweeping House-passed gun control legislation that Republicans opposed, 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.
For some families of those lost in Uvalde, the Senate deal would not go nearly far enough. Leonard Sandoval, whose 10-year-old grandson Xavier Lopez died at Robb Elementary School last month, said what he really wanted was a ban on semiautomatic weapons like the ones used in almost every major mass shooting of the last decade.
“Those weapons are for soldiers, not for someone to use on us,” Mr. Sandoval said. “They need to ban those first. These are the weapons they have used in many of these shootings. People don’t need to have access to them. They are for wars.”
Others whose loved ones have perished from gun violence said they were focused on keeping together the fragile coalition in the Senate that forged the compromise, especially keeping the Republicans on board.
“They will be under tremendous pressure,” said Garnell Whitfield Jr., whose mother, Ruth Whitfield, was shot and killed in Buffalo. “The goal is to make sure that they stay strong moving forward.”
Reporting was contributed by Luke Broadwater from Washington, Edgar Sandoval from San Antonio, and Ashley Southall and Ali Watkins from New York.