The ad buy, which kicks off Thursday, will target Ohio and hits rival Hillary Clinton on Benghazi.
Jennifer Baker, director of public affairs for the NRA's lobbying arm, said the purchase is just "the initial buy" of what will be an aggressive campaign to defeat Clinton in November.
"For law abiding gun owners and people who support the second amendment, the stakes in this election have never been higher," Baker said.
Approximately $1.3 million of the advertising dollars will be focused on Ohio, according to a breakdown reported by NBC News. The rest of the money will target GOP strongholds in Colorado, Florida, Maine, Nevada, Virginia, and Pennsylvania.
Baker said the buy will largely focus on broadcast television in battleground states, and about $600,000 will be spent on cable television nationally and on local sports networks, according to an NBC News report.
The NRA ad does not explicitly mention gun issues — Baker declined to explain the reasoning behind focusing on Benghazi — but the ad does come as the NRA is under pressure. Democrats recently held a sit-in the House of Representatives to argue for restrictions on gun purchases in the wake of the Orlando nightclub massacre. A recent CBS poll also found American gun ownership levels are at their lowest in nearly 40 years.
The buy shows the NRA is stepping up as some of the other typical heavyweights in Republican advertising are staying on the sidelines of the presidential election so far this cycle. The Koch Brothers' Americans for Prosperity are focusing their vast financial firepower on vulnerable Republicans in Senate races, and the head of the Karl Rove-backed American Crossroads said in May the group was also prioritizing Senate races.
Trump previously posted anemic fundraising numbers for the month of May, although he has begun stepping up his own fundraising in recent days.