Sen. Lindsey GrahamLindsey Olin GrahamSenate GOP urges Trump administration to work closely with Congress on NAFTA Graham: Trump will 'end North Korea’s threat to the American homeland' in his first term Sunday shows preview: Lawmakers weigh in after Texas school shooting MORE (R-S.C.) is going on the air early to tout his conservative bona fides months ahead of his June primary election.

The ad opens by highlighting Graham's fights with the Obama administration over the attacks in Benghazi, Libya, and ObamaCare, and ties him to former Sen. Jim DeMint (R-S.C.), who is popular with the Tea Party.

Graham has faced criticism from the right for his positions on immigration and climate change, and is facing five primary opponents, none of whom have much money for the race.

His opening ad salvo, which The State says will run on TV and radio statewide, is likely just the first push in a sustained effort to pump up his conservative bona fides ahead of the primary. Graham has $7.6 million in the bank, much more than any of his opponents.

"DeMint, Graham take GOP lead against healthcare bill," flashes a headline from a local publication as a narrator says Graham "opposed ObamaCare from day one" and says he "led the fight on Benghazi."

Some conservatives hope they can knock off the senator by holding him below 50 percent and forcing him into a runoff two weeks later, but the fractured field of candidates running against him has made that more difficult. 

DeMint, who now heads the conservative Heritage Foundation, has not endorsed in the race and is expected to stay neutral.

"He opposed ObamaCare from Day One, voting against it, then to repeal it. He led the fight on Benghazi, demanding answers when our people died," the ad's narrator says. "He's been a champion for the military, our veterans and a fighter for South Carolina jobs. Sen. Lindsey Graham: A conservative leader who gets things done."