An emotional President Obama announced plans to tighten gun control regulations Tuesday in a renewed effort to address the litany of mass shootings, a move that local supporters said could reduce the flow of guns to Massachusetts from other New England states.

Wiping away tears as he recalled the 20 first-graders killed at Sandy Hook Elementary School in Connecticut in 2012, Obama called his plans “common sense reforms’’ that would make it more difficult for dangerous people to obtain weapons by strengthening enforcement of background check requirements. The executive measures he announced would allow him to sidestep Congress, which has been increasingly hostile to gun control legislation.

“We do not have to accept this carnage as the price of freedom,’’ he said at a White House announcement attended by families of gun violence victims and by public officials, including Mayor Martin J. Walsh of Boston. The United States, he said, is the only advanced country that “sees this kind of mass violence erupt with this kind of frequency.’’

‘‘Every time I think about those kids, it gets me mad,’’ Obama said.

Federal law already requires that anyone “in the business’’ of selling firearms conduct background checks, regardless of where the transactions take place. Some dealers at gun shows and on websites contend that they are exempt because they do not sell regularly and consider themselves collectors or hobbyists.

Obama’s executive action Tuesday clarifies that the background check requirement can be applied to those dealers, as well.

That could well have an effect in Massachusetts, which has among the nation’s toughest restrictions, but is surrounded by other New England states that have far more relaxed rules.

Critics have dismissed the steps as modest, but gun-control advocates said they would help deter criminals and those suffering from mental illness from obtaining weapons.

“It holds all gun sellers accountable,’’ said John Rosenthal, the founder of Stop Handgun Violence, a Boston-based group. “This will save lives.’’

Rosenthal, who attended Obama’s announcement at the White House, said an estimated 50 percent of all gun sales occur without background checks. Only federally licensed gun dealers are required to conduct background checks, leaving purchases made by unlicensed dealers at gun shows and online largely unregulated.

“It’s a loophole big enough to drive a Sherman tank through,’’ he said. “It’s no wonder we have an epidemic.’’

The National Rifle Association, the country’s largest gun-rights group, said the proposed executive actions were “ripe for abuse’’ by an administration that has “made no secret of its contempt for the Second Amendment.’’

“Once again, President Obama has chosen to engage in political rhetoric, instead of offering meaningful solutions to our nation’s pressing problems,’’ said the NRA’s Chris W. Cox.

Jim Wallace of the Gun Owners’ Action League of Massachusetts dismissed the moves as “a dog-and-pony show’’ that would do little to keep guns out of the wrong hands.

“People who are going to avoid the system are going to avoid the system,’’ he said. Wallace praised one aspect of the Obama administration’s proposal — to streamline background checks — but said attempting to regulate private sales between individual buyers was unrealistic.

“Good luck trying to regulate that,’’ he said.

After the Newtown, Conn., shootings, Obama attempted to pass gun control through Congress, but the effort collapsed in the Senate.

Since then, the White House has said it was thoroughly researching the president’s powers to identify every legal step he could take on his own. A more recent spate of gun-related atrocities, including in San Bernardino, Calif., has spurred the administration to give the issue another look.

Republicans on the campaign trail and in Congress dismissed the latest proposal.

‘‘Rather than focus on criminals and terrorists, he goes after the most law-abiding of citizens,’’ said House Speaker Paul Ryan, a Republican. ‘‘His words and actions amount to a form of intimidation that undermines liberty.’’

Only Congress can enact more sweeping changes, but Obama said he is using the tools that are available to him.

Gun control advocates said close enforcement of the new regulations would be crucial, and the Obama administration said the FBI would overhaul the background check system to make it more efficient. It would also seek to hire more than 230 new employees to help process the checks.

Obama’s new regulations don’t specify how many firearms a dealer must sell before he is required to conduct a background check.

Laura Cutilletta, senior staff attorney at the Law Center to Prevent Gun Violence in San Francisco, said the regulations would require more dealers to obtain a federal license and conduct background checks for sales. Many gun sellers — at shows and on websites — have avoided the requirement by saying they are private collectors or hobbyists.

“This would better define, and expand, who is in the business’’ of selling guns,’’ Cutilletta said.

In Massachusetts, gun owners must pass state and federal background checks to obtain a license, which is required for any gun purchase.

But Walsh said that nearly 70 percent of guns used in Boston crimes come from outside Massachusetts, making tighter national regulation crucial.

“Guns move across city and state lines and all too easily from legal ownership to criminal possession,’’ he said.

The laws are far less rigorous nearby, say people who study the gun problem.

“It’s not a very long drive to Rhode Island or New Hampshire,’’ said Jack McDevitt, associate dean for research and graduate studies at Northeastern University and chairman of the gun violence task force assembled by House Speaker Robert DeLeo. “This will start to put a floor down on who can acquire guns across the country.’’

DeLeo said the Obama plan complements the state’s landmark 2014 gun law, which added the state to a national database for background checks and allowed police chiefs to go to court to keep weapons away from people they deem dangerous.

As Obama announced the new regulations, shares in Smith & Wesson Holding Corp. rose sharply on news that the handgun producer will bring in far more revenue than forecast. Gun sales surged last month amid discussion of stricter gun control measures following the terrorist shooting in San Bernardino.

Material from the Associated Press and Bloomberg News was used in this report. Peter Schworm can be reached at schworm@globe.com. Follow him on Twitter @globepete.