Though his ad might have seemed like an endorsement for Sen. Lindsey GrahamLindsey GrahamGraham: Calling climate change a 'hoax' bad for GOP Graham: Comey should be held accountable for acting on bad intel Trump got harsher GOP reception than Bush on budget MORE (R-S.C.), Mike Huckabee is insisting he didn't wade into the state's contentious GOP primary. 

The former Republican presidential candidate and Arkansas governor now says his appearance in a video praising Graham's commitment to fight "radical Islam" does not mean he's throwing his weight behind the state's senior senator.

In the ad — which aired during the Capital One Bowl game between the South Carolina and Wisconsin, according to The State —  Huckabee praises Graham for his work on foreign policy issues. The video was paid for by the South Carolina Conservative Action Alliance. 

"Ronald Reagan's leadership brought down the Berlin Wall and crushed the Soviet empire. The enemy of our time is radical Islam. And there's a leader in South Carolina who knows what it takes to win: Lindsey Graham. He demands answers on Benghazi, backs our allies in Israel, and he fights for a strong national defense," Huckabee says in the ad.

But Huckabee, who said during a book tour last month that he's open to another bid for the White House, later posted a message to his website clarifying that the message wasn't intended as a campaign endorsement.

"To be clear, I haven't endorsed Lindsey Graham for Senate," Huckabee wrote. "Last year, I voiced an ad thanking him for support of Israel. It was not an endorsement for his reelection. In fact, I don't plan to endorse anyone in SC Senate race in the primary but I will certainly help in the general election if asked."

At least four primary opponents — state Sen. Lee Bright, ice cream truck businessman Richard Cash, U.S. Army veteran Bill Connor and Nancy Mace, the first female graduate of The Citadel — have emerged to challenge Graham from the right. 

They argue Graham's willingness to negotiate with Democrats on issues like immigration have left the veteran Republican vulnerable in the deeply red state. Tea Party favorites such as Reps. Jeff Duncan and Trey GowdyTrey GowdyMedia overplayed hand trying to connect Trump to Gianforte McCain: Dems killed Lieberman’s FBI shot Budowsky: GOP summer of scandal MORE, and Sen. Tim ScottTim ScottGOP senators distance themselves from House ObamaCare repeal bill GOP senators lukewarm to lawmaker leading FBI Senate GOP defends writing its healthcare bill in private MORE have prevailed in their contests over establishment candidates in recent years. The state's former senator Jim DeMint, who resigned in 2012 to become president of the Heritage Foundation, remains popular among the party's conservative wing. 

Still, Graham retains a sizable fundraising advantage with more than $7 million in the bank, and many GOP operatives in the state doubt he's in much danger. But if a strong opponent emerges, or if he's forced into a two-week runoff sprint, there's a risk that outside groups like FreedomWorks, the Club for Growth or the Senate Conservatives Fund could enter the fray and blunt Graham's financial advantage.

The association with Graham could prove a vulnerability for Huckabee among Republican voters in the state's important presidential primary. Huckabee lost the state to Sen. John McCainJohn McCainMcCain: Putin a greater threat than ISIS Trump’s defense spending boom that wasn’t Defense hawks gird for budget brawl MORE (R-Ariz.) by 3 percentage points in the 2008 contest.