◆ Democrats want to revive assault weapons ban.

WASHINGTON — As Congress wrestles with how to respond to a wave of mass shootings, leading Democrats are raising an idea once viewed as political suicide: reviving the ban on assault weapons, which barred Americans from purchasing certain military-style firearms for a decade until Republicans let it expire in 2004.

The idea is gaining traction on the presidential campaign trail, where former Vice President Joe Biden, an architect of the original 1994 assault weapons ban, and nearly all of the other Democratic candidates have embraced it.

In an opinion piece published Monday in the New York Times, Biden vowed to make the 1994 law “even stronger,” adding, “We have to get these weapons of war off our streets.”

Two centrist Democrats who flipped Republican House seats last year — Reps. Mikie Sherrill of New Jersey and Jason Crow of Colorado — also came out Monday in favor of the ban. Both are military veterans; Crow ousted a Republican incumbent after running on an aggressive platform of combating gun violence.

With strong opposition from Republicans, who are in charge of the Senate, and President Donald Trump in the White House, an assault weapons ban has virtually no chance of being signed into law before 2021. Nearly 200 House Democrats are backing legislation to reinstate the ban, which is not enough to even pass the House.

Still, the push by prominent Democrats does force the issue onto the 2020 campaign agenda. And it demonstrates just how much the politics of gun safety have changed over the last several years — and especially the last few weeks, after the back-toback massacres in El Paso and Dayton, Ohio.

“The public has supported the assault weapons ban, and they really support it when you remind them that we had it already and that these are weapons that the military uses,” said Celinda Lake, a Democratic pollster. “The intensity has always been on the anti-gun-control side. Now the intensity is shifting onto the other side and the refrain out of Dayton — which is exactly the refrain the public has — is, ‘Do something.’ ”

Polls show that a majority of Americans support an assault weapons ban, but the support is not bipartisan. A July poll by National Public Radio found that 57 percent of respondents were in favor of a ban. But while 83 percent of Democrats said they were in favor, just 29 percent of Republicans supported it.