WASHINGTON — Senate Minority Leader Mitch McConnell announced his support Tuesday for his chamber’s emerging bipartisan gun agreement, boosting momentum for modest but notable election-year action by Congress on an issue that’s deadlocked lawmakers for three decades.

Senate Minority Leader Mitch McConnell of Kentucky on Capitol Hill in Washington on Thursday. Patrick Semansky/Associated Press

The Kentucky Republican said he hoped an ouline of the accord, released Sunday by 10 Democrats and 10 Republicans, would be translated into legislation and enacted. McConnell’s backing was the latest indication that last month’s gun massacres in Buffalo, New York, and Uvalde, Texas, had reconfigured the political calculations for some in the Republican after years of steadfastly opposing even incremental tightening of firearms curbs.

“If this framework becomes the actual piece of legislation, it’s a step forward, a step forward on a bipartisan basis,” McConnell told reporters. He said the proposal “further demonstrates to the American people” that lawmakers can work together on significant issues “to make progress for the country.”

McConnell’s comments were striking, coming five months before midterm elections in which Republicans hope to win control of the Senate and seem likely to win a majority in the House. For years, Republican candidates could risk their careers by defying the views of the party’s loyal gun-owning and rural voters, who oppose moves seen as threatening their ownership and use of firearms.

McConnell seemed to suggest that backing this gun measure might even help some Republicans’ prospects in November. While he said senators should take a position “based upon the views of their states,” he said Sen. John Cornyn, R-Texas, a chief architect of the deal, presented Republican polling data at a closed-door senators’ lunch saying support among gun owners for the agreement’s provisions is “off the charts, overwhelming.”

The plan would for the first time make the juvenile records of gun buyers under age 21 part of required background checks. Money would be sent to states for mental health and school security programs and for incentives to enforce or enact local “red flag” laws that let authorities win court approval to temporarily remove guns from people considered dangerous.

Senators and aides hope to translate their broad agreement into legislation in days, in hopes that Congress could approve it before leaving for its July 4 recess. Both sides acknowledge that is a difficult process that could encounter disputes and delays.

Some Republicans expressed unhappiness with the plan Tuesday, with much criticism aimed at its encouragement of “red flag” laws. Nineteen states mostly dominated by Democrats and the District of Columbia have them, but Republicans have blocked efforts in Congress to pass federal legislation on the subject.

“If we’re not going to pass a federal red flag law, and we shouldn’t, why would we incentivize states to do something that we think is a bad idea?” said Sen. Kevin Cramer, R-N.D.

“I don’t know what we can do in view of the Constitution,” Sen. Richard Shelby, R-Ala., said of the overall agreement, citing the Second Amendment right to bear arms.

Cornyn defended the plan’s “red flag” proposal, saying it would create no national requirements for such laws. He said it gives “every state regardless of whether it has a ‘red flag’ law or not” money for programs aimed at improving public safety and helping troubled people get assistance. Texas does not have a “red flag” law.

McConnell made clear he would only go so far in restricting firearms.

Asked by a reporter why the federal minimum age is 21 for tobacco sales but 18 to buy rifles, he answered, “Good try.” He added that including state and local juvenile records in background checks for the youngest guy buyers was “a step in the right direction.”

The alleged shooters in Buffalo, where 10 people were killed, and Uvalde, where 19 school children and two teachers were slain, were both 18 years old, a common profile for many mass shooters.

A final agreement on overall legislation would be expected to receive solid support from Democrats. But it would need at least 10 Republican votes to reach the Senate’s usual 60 vote threshold, and McConnell’s plaudits raised hopes that Republican backing would grow beyond that.

The framework also broadens the type of domestic abusers who’d be prohibited from buying guns, require more firearms sellers to conduct background checks and impose tougher penalties on gun traffickers.

The National Rifle Association said Sunday it wouldn’t take a position on the proposal until full legislation is produced. It warned it would oppose “gun control policies” or infringements on people’s “fundamental right to protect themselves.”

The pro-gun lobby still has political muscle from its millions of dedicated members, who vote heavily on firearms issues. But Republican support for the new package is the latest threat to its power following recent financial scandals and lawsuits.

Approval seems likely by the Democratic-run House, where Speaker Nancy Pelosi, D-Calif., has praised the measure as a first step toward strong restrictions in the future.

Senate Majority Leader Chuck Schumer, D-N.Y., said he would schedule votes on the legislation as soon as it is ready. He contrasted recent days’ progress with Congress’ failure to act after a parade of mass shootings in recent decades.

“After Uvalde and Buffalo, perhaps this time could be different. To many senators on both sides, this debate certainly feels different,” Schumer said.

Congress’ last major gun measure was an assault weapons ban that took effect in 1994 but expired 10 years later.