NRA drops last-minute money for GOP candidate into Pennsylvania special election It is the only political spending the pro-gun group has reported since Parkland.

The National Rifle Association has engaged in an under-the-radar spending campaign for Republican candidate Rick Saccone in Pennsylvania’s Tuesday special election.

It is the only federal political spending the pro-gun group has reported since the Feb. 14 shooting at Marjory Stoneman Douglas High School in Parkland, Fla., according to FEC reports.

The NRA spent $7,868 in support of Saccone but the money wasn’t seen in a high-profile venture like TV ads or get-out-the-vote efforts. Most of it - $7,532 - was spent on mailings scheduled to be distributed in the district on Monday. The remaining $336 was spent on phone banking earlier this month, according to campaign finance filings.

The group confirmed the existence of the mailer to ABC News but declined to describe it or where it was sent in the 18th Congressional District. The NRA has endorsed Saccone, who has an A+ rating from the group, and has donated $2,450 to his campaign.

And it isn't the only spending entity making this an issue in the race.

The Congressional Leadership Fund, a pro-Republican super PAC, also has highlighted the issue, which is in the national spotlight after Florida passed new school safety rules and President Donald Trump laid out his support for legislation currently being considered by Congress, which includes improving background checks and providing grants to states for anti-school-violence plans.

The campaign tactics also come as Republicans go all-in for this special election contest in a district Trump won by 20 points in 2016 and won’t exist in the November election because of redistricting.

Democrat Conor Lamb has run a strong race, putting a seat in play for the party where it should not be competitive. And the national GOP has already started the post-election night spin, talking down Saccone as a bad candidate who couldn’t fund-raise or campaign properly.

For both sides the stakes are high. If Lamb wins, Democrats will claim their candidates can run and win anywhere in the country – even ruby-red Trump districts - which will boost their odds in retaking control of the House this fall. If Saccone wins, Republicans will argue they can keep the House even with the president’s low approval ratings and the consistent flow of chaos and controversies that come out of the Trump White House.

Money has poured into the contest.

Lamb raised more than $3.6 million since January, compared to Saccone's haul of just under $1 million over the same time period, according to FEC data.

Outside groups have made up for Saccone’s abysmal fundraising numbers. The GOP nominee has been helped by more than $10.6 million in spending from super PACs and outside groups.

Pro-Lamb outside groups have spent about $1.7 million.

Gun rights are a big issue in this red district, which contains parts of rural south-western Pennsylvania, where hunting is a huge tradition.

Lamb has emphasized his support for Second Amendment rights. His first campaign ad, a “bio” ad to introduce himself to voters, included a photo of him shooting a rifle.

And, in the aftermath of the Parkland shooting, Lamb called for tougher background checks but not stricter gun laws.

Additionally, at a rally on Sunday, United Mine Workers President Cecil Roberts called Lamb a "God-fearing, union-supporting, gun-owning Democrat.”

The CLF mailer, ironically, highlights that record. The flyer, obtained by ABC News, reads: “THANK YOU CONOR LAMB FOR OPPOSING GUN RESTRICTIONS.”

But the recipients were Democrats in Allegheny County, likely in hopes of suppressing turnout among the more liberal Democrats who live in the Pittsburgh suburbs that make up that part of the district; a group of voters that supports more restrictions on guns.

“Our job is to make sure voters in Pennsylvania’s 18th District know where Conor Lamb stands on important issues of the day. This mailer was sent to voters who might find his views on the Second Amendment of note,” said CLF spokeswoman Courtney Alexander in a statement.

Lara Putnam, a professor at the University of Pittsburgh, said that part of the 18th Congressional District is more liberal and more likely to favor gun control.

“If it’s going to the northern part of the district is probably says Conor Lamb supports guns and it’s trying to get the sort of suburban progressive Democrats in the northern part of the district to stay home,” Putnam, who lives just outside the district and has canvassed for Lamb, told ABC News.

But the rest of the district is composed of more rural areas that strongly support gun rights, including parts of Washington, Greene, and Westmoreland Counties.

In addition to the last-minute mailers, Saccone on Monday brought in Donald Trump Jr. to campaign for him. On Saturday Trump was in the district. Lamb spent the weekend highlighting his support from unions.

Polls close at 8 p.m. EDT in Pennsylvania on Tuesday. Please check ABCNews.com for election results.

ABC News’ Soorin Kim contributed to this report.

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