Democrats know they have a winning issue. When the entire country is convulsed by back-to-back massacres in Dayton, Ohio, and El Paso, and 90 percent or so of Americans favor an array of gun measures, they have every reason to push as hard as they can.

At a news conference Monday with Democrats whose constituents were recently affected by gun violence — Rep. Veronica Escobar (D-Tex.), who represents El Paso; Nan Whaley, the Democratic mayor of Dayton; and Sen. Sherrod Brown (D-Ohio) — House Speaker Nancy Pelosi (D-Calif.) declared: “Ninety percent, at least, of the public supports it, including gun owners, members of the NRA and the rest. So, when they say the president’s base is opposed to it, 90-some percent of the American people support it. What courage does it take to support legislation that will save lives?” She continued, “So, here we are once again asking the Grim Reaper, informing the Grim Reaper that this bill, these bills are alive and well in the public, that public opinion, public sentiment, will weigh in. And, as I have said in our meetings across the country, we will make this issue too hot for him to handle.”

In other words, this is a no-win for Republicans. Either they grudgingly go along, getting grief from their Trumpian base, or they dig in, making worse their position with suburban and college-educated voters, especially women.

On this bill in particular, the case for Democrats is quite easy since the Republicans have already accepted some background checks. “It’s very simple: online sales, person-to-person sales — which is how one of the most recent gun violence episodes took place, because somebody bought it from a person — person-to-person, online and gun shows — again, as was indicated, whose purpose was something quite different at the time,” Pelosi explained. “So, this isn’t radical. It’s just an expansion of what has been successful already.”

It remains to be seen whether the National Rifle Association will finally falter this time around. However, Senate Minority Leader Charles E. Schumer (D-N.Y.) exuded confidence at the joint news conference. “Never have we had 93 percent of the American people for background checks,” he said. "Never have [we] had 80 percent of gun owners for background checks. Never have we had so many folks in the NRA for background checks.”

Brown chimed in: “Why is this different now from what it was a month ago? It’s different because Republican senator after Republican senator in states like Maine and North Carolina and Arizona and Colorado — that are fearful of what’s going to happen in their reelection fights — are out campaigning in August and they’re hearing from voter after voter after voter. You’ve got to do something.”

Democrats would surely love to break the back of the NRA on guns, a move that would send a tremor throughout the right-wing ecosystem. But if President Trump, Senate Majority Leader Mitch McConnell (R-Ky.) and the NRA once more block the popular will, Democrats are optimistic it will be an anvil around their necks, not only in the presidential election but in every House and Senate race. And once they have this one under their belts, they might even get serious about banning guns of war on our streets at home.

Read more:

The Post’s View: No, Sens. McConnell and Blunt. You’re the ones who need to step up.

Nan Whaley: Dayton’s mayor: We owe it to mass shooting victims to take action on gun control

Fred Hiatt: There’s never been a president like Trump. Just look at his gun-control record.

Paul Waldman: Democrats have lots of gun proposals. Why aren’t we talking about the most important one?

Howell Raines: To fix our gun crisis, we should revert to ’60s gun laws

Marianne Williamson: America doesn’t just have a gun crisis. It has a culture crisis.