WASHINGTON — As the first bipartisan agreement on gun safety measures in years takes shape on Capitol Hill, Republicans and Democrats are laboring to keep their compromise on track by sending disparate messages about its scope and implications.
Democrats, who wanted far more sweeping gun control steps, have noted that if passed, it would be the most significant legislation on the issue in decades. Republicans, fearful of crossing their anti-gun-control base, are focusing instead on the proposals they kept out of the agreement, including bans on weapons or ammunition and raising the age for purchasing firearms.
The contrast between how Democratic and Republican proponents are describing the proposal — big and monumental versus targeted and limited in scope — reflects the tricky politics surrounding the issue, and the fragility of the coalition that has come together to try to break a yearslong stalemate.
“It will unquestionably save lives and would be the most significant action on guns that the Senate has taken in nearly three decades,” Senator Chuck Schumer, Democrat of New York and the majority leader, said on Tuesday.
Not long before, Senator John Cornyn, the Texas Republican who played a crucial role in the talks, displayed an oversize chart on the Senate floor headlined “Ideas Rejected in Negotiations,” as he carefully explained what his party had agreed to and — just as important — what it had not. He noted that the Democratic proposals rejected by Republicans included universal background checks, a high-capacity magazine ban and an assault weapons ban for 18- to 21-year-olds.
Senator Mitch McConnell of Kentucky, the minority leader, said on Tuesday that he was “comfortable” with the bipartisan framework that had emerged and would support a final bill that followed its parameters, another indication that Republicans are aiming to hold together the coalition behind the deal and demonstrate to their colleagues that it would be politically safe to support it.
The effort comes at a critical stage, as negotiators in both parties are toiling to translate a deal in principle into legislative language that can draw 60 votes on the Senate floor. The measure under discussion would require enhanced background checks for prospective gun buyers younger than 21, make it more difficult for domestic abusers to get firearms and provide federal grants to states to enact so-called red-flag laws to keep guns out of the hands of dangerous people, among other steps.
Democrats entered negotiations two weeks ago with modest hopes, eager simply to demonstrate that it was possible to break the impasse and pass some sort of gun safety legislation in the wake of a mass shooting, and conceding that it would have to be limited in order to attract enough Republican support to pass.
The political stakes were high, even if expectations of any major breakthrough were not. With President Biden’s poll numbers sagging as he struggles to advance the bulk of his agenda, he and Democrats are desperate for any legislative victory to buoy his presidency and their prospects for the midterm congressional elections.
At the same time, after the shooting massacre of 19 children and two teachers at an elementary school in Uvalde, Texas, Republicans recognized that they needed to catch up with their own political reality: that the vast majority of voters, including their own, support at least some gun safety measures, including enhanced background checks.
Still, they have been girding against a backlash on their right flank by trying to play down the idea that they gave any ground to Democrats on the issue of guns.
Appearing on Fox News this week, Mr. Cornyn assured viewers that “states that don’t have red-flag laws will not be compelled to pass them” and that the proposal included “no new restrictions for law-abiding gun owners.”
“Part of the problem we’ve encountered is that people are reading things into the bill that aren’t there, so this is a process of trying to explain what’s in and what’s out,” Mr. Cornyn said in a brief interview on Tuesday.
That is a matter of political necessity for Republicans as the right wing mobilizes against the compromise. Representative Lauren Boebert, Republican of Colorado, has branded the senators who have signed on as “squishy RINOs” — Republicans in name only — while the American Firearms Association, a grass-roots gun rights group that is fund-raising off outrage over a potential deal, referred to the Republicans involved as “treacherous bastards” who want to “disarm this entire country.”
A spokeswoman for former President Donald J. Trump said he was livid at the Republicans who had embraced the framework. “We have to stop these RINOs from joining the Democrats,” the spokeswoman, Liz Harrington, said in an interview with a conservative media outlet, asserting that red-flag laws would turn the United States into “the Soviet Union.”
(After back-to-back mass shootings in Dayton, Ohio, and El Paso, Texas, in 2019, Mr. Trump called for red-flag laws.)
“I think we’re more interested in the red wave than we are in red flags, quite honestly,” Senator Kevin Cramer, Republican of North Dakota, said on Tuesday after Mr. Cornyn presented an outline of the emerging bill during a closed-door G.O.P. Senate lunch.
Democrats have their own challenges in staying united behind the proposal, as progressives have raised concerns about its limited scope and approach.
Representative Alexandria Ocasio-Cortez, Democrat of New York, has said she is concerned that the proposal, which would for the first time allow law enforcement to review juvenile and mental health records for gun buyers younger than 21, could lead to the “criminalization” of children.
Mr. Schumer has tried to talk up all that the bill would do, noting the significance of enhanced background checks for people under 21 and closing the so-called boyfriend loophole, a longtime priority for gun safety activists.
Still, critical sticking points remain unresolved.
Mr. Cornyn told reporters on Wednesday that he was concerned that states without red-flag laws would be ineligible to receive funds for crisis intervention programs. Both Democrats and Republicans have also hinted at disagreements about who precisely would be covered by the closing of the boyfriend loophole, which aims to include dating partners in a prohibition against domestic abusers getting guns. The ban currently applies to spouses.
“At some point, if we can’t get to 60, we’re going to have to pare some of it down,” Mr. Cornyn said, warning that the bill-writing stage could stretch into next week.
Senator Christopher S. Murphy of Connecticut, the lead Democratic negotiator, said that he did not expect anything in the framework to fall out of the final bill, and that he was confident it would pass.
As they push divergent messages about what the gun agreement would and would not do, both Democrats and Republicans have a legitimate case to make.
Because the bar for a history-making breakthrough on guns in Congress is low — there has not been significant federal gun legislation passed since 1993 — a modest move still counts as a major moment.
That dynamic may be unsatisfying for Democrats frustrated that they have to accept incremental progress and enact only a fraction of the policies they believe would save lives, but it could amount to a political win-win for them, strategists said.
“They have a major accomplishment to talk about, and they also still have a lot of turf left for a very fertile debate on what else needs to be done to address gun violence and mass shootings,” said Geoff Garin, a Democratic pollster. “The reality of Senator Cornyn’s position is that the provisions that Republicans kept out of the bill are very popular with the large majority of voters. Those are the policies that are going to get litigated in the midterm elections.”
And while the difference in emphasis may reflect how divided the country is on guns, some said it was also a sign of progress.
“The way both Republicans and Democrats are messaging this indicates to me that they’re actually serious about getting something done,” said James P. Manley, a former top adviser to the former majority leader Senator Harry Reid.