Congressional Democrats increasingly frustrated by a string of defeats on gun issues in Washington are scrambling to harness a public outpouring after last week’s sit-in protest on the House floor.

Party leaders are urging members to conduct similar sit-ins around the country as they try to sustain the flash of hard-core activism on the gun issue.

“We don’t have the numbers to get things done, so we have to turn to more dramatic displays to galvanize the public so they can help us pressure the Republicans to do what’s right,” said U.S. Rep. Keith Ellison, D-Minn.

House Minority Leader Nancy Pelosi on Monday wrote a letter to colleagues urging them to hold sit-ins in their districts to build on the momentum of last week’s protest.

The gun issue is looming large in the election year after the Orlando massacre that killed 49 people, along with a string of other recent high-profile shootings.

The issue puts many Democrats in a high-stakes clash with the National Rifle Association, a major campaign contributor that holds considerable power in Congress and has fought hard against restrictive gun laws.

U.S. Rep. Keith Ellison tweeted this photo of himself sitting on the House floor in a protest aimed at forcing a vote on gun control.

Republicans have dismissed the sit-in as a crass political ploy, noting that none of the recent gun proposals rejected in the U.S. Senate would have prohibited the recent Orlando shooter from having legal access to firearms.

The protest was “completely intolerable,” said U.S. Rep. John Kline, R-Minn. “It was very clearly a publicity stunt designed to gain further support from their base and to be used as a fundraising tool.”

Democratic representatives sat in the House chamber for 25 hours last week, criticizing the GOP majority for not allowing votes on measures requiring wider background checks for gun buyers and forbidding terror suspects from purchasing firearms. The Orlando shooter, Omar Mateen, was briefly placed on a terrorist watch list but bought his firearms legally.

Ellison was with the president of the National Iranian American Council when a scheduler gave him a note that said, “Your mom called and wants you on [the] floor!”

The Minneapolis Democrat’s mother is a social worker in Detroit who often sees the effects of gun violence, he said.

Ellison drew gasps on the House floor as he recounted how a man shot six people to death at Accent Signage Systems in Minneapolis in 2012, including owner Reuven Rahamim. The gunman obtained his gun legally.

Ellison said he believes the measures rejected in the Senate are good first steps to get more guns off the streets, even if they might not have specifically prevented the incidents he cited on the House floor.

The gun issue is already playing a role in Minnesota’s congressional races.

Democratic Reps. Betty McCollum and Rick Nolan joined the sit-in, but it is not clear whether they plan to host sit-ins in their districts.

Nolan is facing a fierce re-election battle in northern Minnesota against Republican Stewart Mills, who calls gun ownership a “sacred right” and vows to fight tougher controls.

Democrats trying to win majorities in the House and Senate are making their public appeal as polls nationally, including in a Star Tribune Minnesota Poll earlier this year, show strong support for tougher background checks for firearm purchases.

Kline, who is retiring from the Second Congressional District this year, has been a steady opponent of tougher gun restrictions.

He has received $119,887 in campaign contributions from the gun industry in his 14 years in the House, making him the 11th highest recipient of campaign funds from gun rights interests, according to the Center for Responsive Politics.

“I’m a strong supporter of the Second Amendment guaranteeing the right to keep and bear arms, and organizations that recognize my support would like to see me stay in Congress,” Kline said.

The issue is not clear-cut in Minnesota, where many die-hard Democrats are passionate hunters and devoted gun owners.

Angie Craig, the DFL nominee vying to replace Kline, said she supported wider background checks and prohibitions against suspected terrorists from buying firearms.

“Hunting is a way of life in Minnesota,” she said. “My sons hunt. But I think it’s time for a national conversation.”

Her GOP rivals have all expressed unwavering support for gun rights.

And the sit-in did not win universal Democratic support. Minnesota Rep. Collin Peterson, a strong gun rights supporter with high ratings from the NRA, did not join the protest.

Republican Rep. Erik Paulsen, who is facing a tough re-election fight, supports finding a way to keep guns out of the hands of terrorists. A “bipartisan solution that can pass in both the House and the Senate is the only way we are going to get a bill to the president’s desk that will bring us closer to that goal,” a spokesman said via e-mail.

McCollum said her interaction with constituents shows the issue resonates deeply with voters.

“When I got elected, Columbine was the issue, and then it’s been Sandy Hook and then it’s been Virginia Tech … the people who are concerned about this issue have said, ‘When is enough enough?’ ” said McCollum, her voice rising. “This should have been done decades ago.”

She added: “I think it’s a turning point in the gun control debate and I think people all across America are waking up.”

U.S. Sen. Amy Klobuchar, D-Minn., said public pressure might be the best way to bring about change in the face of GOP majorities in Congress.

“I think there’s going to be more and more pushback from regular citizens and I think it’s a possibility that the Republicans in the Senate will work with us and negotiate on some kind of proposal,” said Klobuchar, who stopped by the sit-in to lend support.

Ellison said Minnesotans shouldn’t be surprised to see more public protests on the gun issue play out around the country this summer.

“You’ve got to do something to draw attention to [the issue], and if that means engaging in some attention-getting behavior which some people might dismiss as a stunt, then that’s what it means,” he said. “And I’ll do it and I’ll do it again.”

Staff writer Patrick Condon contributed to this report.