Democrats have renewed their calls for tighter gun control measures in the wake of the mass shooting at a Florida high school last week, vowing to make it a campaign issue this year. Despite minimal success galvanizing voters around such measures in past elections, some advocates are hopeful it could be a more salient issue in this year’s midterms.

It’s difficult to predict if that will be the case, especially when recent history shows that the public’s attention diminishes once the immediate horror and aftermath of a shooting fades. Democrats repeatedly pushed the issue before the 2016 election, holding filibusters in the Senate and a sit-in on the House floor to highlight their concerns, but those efforts made little difference in November.

However, an effort is underway to sustain momentum for change after the Florida shooting. Students from the high school have spoken out on cable news and in op-eds, calling on elected officials to act to prevent such shootings. Students nationwide are planning a walkout next month to protest inaction on gun violence, an event planned by the organizers of the Women's March following Donald Trump's inauguration. And several gun control advocacy groups are organizing a protest -- "March for Our Lives" -- in Washington and across the country later in March to demand action.

TV ads, campaign mail and other direct voter contact will be needed to make the issue a driver of turnout come Election Day, but for now, some Democrats in swing districts see an opportunity to go on offense talking about gun control. Jason Crow, an Amy veteran challenging Rep. Mike Coffman in a suburban Colorado district -- which includes the site of the movie theater mass shooting in 2012 -- issued a press release Thursday calling on Coffman to return donations from the NRA. Crow, who has been endorsed by the gun control group founded by former Rep. Gabby Giffords, said in an interview he wanted to give an aggressive response to the shooting.

“The fact that now we’ve had numerous mass shootings with a lot of people killed in this country in the past year and it’s becoming kind of normalized for folks is not okay,” Crow told RCP. He emphasized his support for expanded background checks, banning military-style assault weapons, and closing gun show loopholes. “What I’m seeing is a more continuous conversation about it. People are talking about it all the time. It’s a concern everywhere I go, every place in the district I go.

“If our leaders are not willing to understand and respect that this is a problem, that this is a crisis, then we need to cast them out,” he added.

Tyler Sandberg, Coffman’s campaign manager, responded that Crow was looking to “score political points over a tragedy.”

“Mike is heartbroken over what happened in Florida and believes this country needs to get laser-focused on mental health reform,” Sandberg said.

Public opinion clearly shows that a majority of Americans support some restrictions on gun purchases: An October Quinnipiac poll showed three in five Americans supported stronger gun measures, and an overwhelming number -- more than 90 percent support universal background checks. But for advocates of these moves, turning them into a top priority that will drive voters to the polls is a critical problem. In a Quinnipiac poll in December, only 6 percent said gun policy should be a top priority for President Trump and Congress, putting it below issues ranging from the economy to foreign policy to the federal budget. Among Democrats, it was the third priority, well below health care and the economy.

However, advocates point to last year’s gubernatorial election in Virginia as evidence the enthusiasm gap has narrowed between NRA supporters and backers of increased gun controls. Democratic Gov. Ralph Northam, who won by nine percentage points, emphasized his support for stricter gun policies throughout the campaign. A former Northam official said they focused heavily on gun measures in the Democratic primary, featuring the issue in every piece of campaign mail and almost every campaign ad.

In the general election, the official said, they did several direct-mail campaigns focusing on guns, and featured the issue in their radio ads. Northam’s personal background as an Army doctor and pediatrician who had treated gunshot victims gave him specific credibility on the issue. Northam also had backing from national gun-safety groups: Everytown for Gun Safety spent nearly $2 million in the race.

Gun policy was the second most important issue for Virginia voters, according to exit polls, and those motivated by it split evenly between Northam and the Republican candidate, Ed Gillespie. In a poll conducted for Everytown after the race, pollster Doug Schoen found that when reminded of Gillespie’s “A” rating from the NRA, 48 percent of voters said they were less likely to vote for him, and 23 percent were more likely.

“If anyone tries to tell you in 2018 that this is the third rail, they’re wrong,” said John Feinblatt, president of Everytown. “And if anyone tries to tell you there is an intensity gap, they’re wrong as well.”

The group started by Giffords, who was shot in 2011, is taking an active role promoting Democratic candidates who back the issue. It has endorsed seven Democratic House candidates and three gubernatorial candidates so far this cycle, including several in competitive primary elections. Gil Cisneros, a Democrat running in a crowded primary in a targeted California House district, highlighted his endorsement from the group in a Facebook post last week calling for an assault weapons ban and universal background checks. One of the other Democrats in the race, pediatrician Mai Khanh Tran, released a comprehensive gun control platform Monday.

Isabelle James, the political director for Giffords’ group, said the issue is particularly salient in suburban districts, which are critical to Democrats’ strategy for retaking the House.

“Look at the Twitter feed of any Democrat running in one of these competitive swing districts. They’re saying, ‘Enough is enough, lives are at stake,’ and they’re not following the conventional wisdom to tread lightly on this issue,” James said.

Even rural Democrats are pushing for the party to more aggressively articulate its position on gun control measures. Rep. Cheri Bustos, who represents an Illinois district that voted for Trump in 2016, said no person or organization there is more popular than the NRA. But she still supports background checks, banning bump stocks, and keeping those on the terror watch list from purchasing firearms, and said she would encourage Democrats to proactively articulate their positions to gun owners.

“If we’re going into areas that are mostly Republican and looking them in the eye and answering these questions honestly, hopefully we’ll be okay,” said Bustos(pictured).

But there are signs that, at least in certain parts of the country, Democrats aren’t likely to embrace that message. Conor Lamb, who is running in a Pennsylvania special election next month in a district Trump won by 20 points, featured himself shooting a rifle in his campaign introduction video. According to the Pittsburgh Post-Gazette, Lamb said he would work to prevent people with mental illness from obtaining guns.

The issue is slightly more complex in Senate races, where the majority of Democratic incumbents are running in states that backed Trump in 2016 and are more heavily pro-gun. But those senators differ greatly on the issue. Sen. Joe Manchin of West Virginia, for example, featured himself shooting up a cap-and-trade energy bill – and touting his NRA endorsement -- in a 2010 ad, but he also co-sponsored background check legislation that failed in 2013.

A fellow sponsor of that legislation was Pennsylvania Republican Sen. Pat Toomey, who was endorsed by several gun control advocacy groups in 2016, helping him secure re-election to a second term. All of the Democratic senators up for re-election this year, with the exception of North Dakota Sen. Heidi Heitkamp, supported the background check legislation.

Heitkamp also voted against a measure proposed by Democrats in 2015 that allowed law enforcement to block anyone on the terror watch list from purchasing guns, though she then co-sponsored a more tailored version blocking people on the no-fly list from buying guns (that bill also failed in the Senate).

Missouri Sen. Claire McCaskill, who is one of Republicans’ top targets in 2018, was emphatic in her support for some gun safety measures in a brief interview on Capitol Hill, including expanding background checks, blocking terror suspects from purchasing guns, and banning bump stocks -- the device used in the Las Vegas shooting that enabled a semi-automatic weapon to function as a fully automatic. She emphasized that she grew up around -- and was comfortable around -- guns, but said most people in Missouri who own firearms legally also want more gun safety measures. She said she isn’t concerned her position would energize Republicans who want to vote her out of office this year.

“I’ve got to look in the mirror every morning. This job is difficult, but if you’re not pushing for things you believe in, then what’s the point of doing it?” McCaskill said. “The goal of being here is not just to get re-elected. The goal of being here is to try to accomplish things you believe in. And I think some gun safety is needed in this country.”