Former Alaska Sen. Mike Gravel is contemplating a primary challenge to President Obama.

Gravel, who ran for president in 2008, won't rule out a primary challenge to Obama in 2012.

"Both are possible," he told the Daily Caller.

Obama has been taking heat recently from the liberal wing of the Democratic Party, which was angered by his compromise with the GOP over extensions of the Bush-era tax rates for top income earners. 

While Gravel mulls his challenge, he made it clear he doesn't think Sarah Palin has a chance of defeating the president.

Gravel called the former Alaska governor a "very talented politician," but added: "Policy wise and intellectually, I think she leaves a great deal to be desired."

"I don't think she could beat Obama," he said.

Since his bid for the White House ended in 2008, Gravel has spoken increasingly about conspiracy theories surrounding 9/11 and called for an investigation into the attacks. He defended his suspicions in the interview.

"Individuals in and out of government may certainly have participated with the obviously known perpetrators of this dastardly act," Gravel told the website. "Suspicions abound over the analysis presented by government. Obviously an act that has triggered three wars, Afghan, Iraqi and the continuing War on Terror, should be extensively investigated, which was not done and which the government avoids addressing."

Should Gravel decide to run, his supporters would expect an unconventional campaign similar to the one that produced the famous "Rock" video below.