Bill Ayers, whose relationship with President Obama was the subject of much intrigue during Obama's 2008 presidential campaign, now says the president should be tried for war crimes.

Ayers, the former Weather Underground member and University of Illinois at Chicago professor, told Real Clear Politics that Obama is "absolutely" engaged in terrorist activity by using drones and "absolutely" should be tried for war crimes.

"Every president in this century should be put on trial," Ayers said. "Every one of them goes into an office dripping with blood and then adds to it. And, yes, I think that these are war crimes. I think that they're acts of terror."

Ayers said he would give Obama a failing grade for his presidency but praised his personal style.

"I like him personally," Ayers said. "I mean, he's a really good guy."

Conservatives alleged during the 2008 campaign that Obama's ties to Ayers belied his extreme ideology and sought to connect him to Ayers frequently, though Obama said the two of them were never close.