Democrats have found their latest dose of political adrenaline in the fight over tougher gun restrictions, appearing to have Republicans on the defensive following their slow-moving response to the massacre of 17 at a Florida high school on Feb. 14.

But there are also a fair number of Democrats running for Congress with mixed views on the issue, sounding quite different from those in the party who are angling for the 2020 presidential nomination.

The most noticeable example is Conor Lamb, a 33-year-old from outside Pittsburgh with a sterling résumé running in a special House election next month. Lamb served as a captain in the Marine Corps until 2013, when he went on to serve as a federal prosecutor focusing on opioid crimes.

Lamb also likes guns and does not believe in banning any weapons, even the type of “military-style’” weapon used in Florida last week. He does not support new limits on the size of ammunition clips.

Frustration is boiling over on both ends of the political spectrum at the inability to stop mass shootings, but many still can't agree on a path forward. (Jenny Starrs/The Washington Post)

“I think the problem of crime prevention is much more complex than banning individual guns,” he said at Monday’s debate with the Republican nominee, state Rep. Rick Saccone (R).

Lamb supports an enhanced background check system along the lines of what Sens. Patrick J. Toomey (R-Pa.) and Joe Manchin III (D-W. Va.) have proposed, but not much else. He strikes a measured tone that is at odds with most Democrats who are pounding their chests at years of inaction on gun laws.

“I recognize that there is great passion on both sides of the gun-control debate,” he said.

It’s not surprising he has struck this pose. Pennsylvania’s 18th Congressional District gave President Trump a sweeping margin in 2016, when the longtime GOP incumbent, Tim Murphy, won by acclamation as the Democrats did not bother to field a candidate.

After Murphy resigned last year amid a personal scandal, Lamb jumped into the race and made it surprisingly competitive, softening the liberal edges on issues such as guns in a region where National Rifle Association memberships and hunting licenses are ingrained in the culture.

He is not alone in being something of an apostate on guns. Democrats are fielding a number of House candidates who have mixed records on guns, if not outright praise from the NRA.

The Democratic Congressional Campaign Committee has touted its recruitment of Paul Davis to run in a conservative-leaning district in Kansas as one of its finest recruits. He narrowly lost the 2014 governor’s race and is viewed as a moderate who can appeal to the voters there. Though he did not get the NRA’s endorsement in 2014, Davis had a B rating from the group.

In southern New Jersey, Democrats have mobilized around state Sen. Jeff Van Drew to run for a seat in Congress that a veteran Republican is leaving behind, presenting one of the party’s best pickup opportunities. Van Drew won reelection to his state seat last fall with an A rating from the NRA.

Needing 24 seats to reclaim the House majority, Democrats feel they need to win in some of these rural districts for total victory, so gun positions are not a litmus test.

To be sure, the focus of their effort is in winning over suburban districts, particularly the several dozen that either favored Democrat Hillary Clinton in 2016 or only narrowly gave Trump a victory.

In those places, Democrats are seeing some candidates embrace a more aggressive approach to the gun issue, with Jason Crow in the Denver suburbs leading that charge. A former Army captain, Crow is running in the district that was home to the 2012 Aurora movie theater shooting that left 12 dead.

He supports a ban on the type of weapons used in last week’s shooting and he has called for his opponent, five-term Rep. Mike Coffman (R), to give away the more than $30,000 in NRA donations he has received in his campaigns.

Crow is hitting the pulse of most Democrats at this moment.

“A tectonic shift is underway on guns. Democrats have tried making nice with the NRA and been burned again and again,” said Adam Jentleson, a strategist at Democracy Forward, a liberal research group. “More and more Democrats are coming around to seeing that there’s no upside to courting the NRA — they’re going to spend millions casting you as a gun-grabber regardless of your actual position, so what’s the point?”

Jentleson had a front-row seat for one of those “making nice” efforts as a senior adviser to Harry M. Reid (D-Nev.) while he served as Senate majority leader. In 2009 and 2010, ahead of a tough reelection, Reid courted the NRA and even hosted Wayne LaPierre, the public face of the group, at a gun range outside Las Vegas.

The group stayed neutral despite Reid’s nearly perfect voting record on guns. After the December 2012 Sandy Hook massacre, Reid abandoned his previous positions and supported a sweeping number of gun-control bills, including an assault-weapons ban and a limitation on clip size.

That same transformation happened with Sen. Kirsten Gillibrand (D-N.Y.), who arrived in Congress in 2007 with dozens of other conservative Democrats who supported gun rights. Now one of the more liberal senators, Gillibrand is frequently mentioned as a possible 2020 presidential candidate and she has crafted the answer to a question she knows she will face: How did she once get an A from the NRA?

Nine years ago, Gillibrand sat down with a mom and a dad, she told CBS’s “Late Show” host, Stephen Colbert, on Tuesday night when he pressed her. The parents had just lost a daughter to a stray bullet. “The anger and fear and resentment in their community because Congress does nothing made me want to change.”

Other 2020 contenders are voicing similar views, but back in southwestern Pennsylvania, Lamb is walking a finer line by citing his time as a prosecutor, believing that only an improvement in existing background check laws are needed.

“Most of the cases that I saw were committed with handguns and by people who were already not allowed to have those firearms,” he said.