"I would say, really, that we knew each other in a professional way on the same level of, say, thousands of other people," he said.
He added, echoing a phrase that Obama used to describe Ayers, "I am a guy around the neighborhood."
Ayers acknowledged that he held a reception in his home when Obama began his political run for state office.
"He was probably in 20 homes that day," Ayers said.
During the campaign, Obama tried to defuse the Ayers issue by condemning Ayers' past actions as "detestable."
"The notion that ... me knowing somebody who engaged in detestable acts 40 years ago, when I was 8 years old, somehow reflects on me and my values, doesn't make much sense," Obama said.
Ayers remained silent during the presidential race, but his proximity to Obama was highlighted on Election Day when the two men nearly ran into each other in the same polling place.
As recently as Wednesday, Palin was still raising the Ayers' issue, telling NBC that she was still concerned about Obama's relationship to the former radical.
Palin was the fiercest critic of the Obama-Ayers tie, accusing Obama of "palling around with a domestic terrorist."
While he was a fugitive, he married Bernardine Dorhn, another member of the Weather Underground.
Obama and Ayers have several connections. The two men have also served on boards together, including the Woods Fund of Chicago and the Chicago Annenberg Challenge.