The University of Chicago-Illinois has opened records that link Senator Barack Obama to 1960s-era radical Bill Ayers.
Ayers also started a terrorist organization called Weather Underground, which took credit for bombings at the Pentagon and U.S. Capitol building.
Click the play button for an analysis by Charles Dunn from the Regent University School of Government
Obama did non-profit work for a group called the Chicago Annenberg Challenge, which Ayers helped start.
Obama's opponents have jumped on these questionable ties with a new TV ad.
"Obama's political career was launched in Ayer's home. And the two served together on a left-wing board. Why would Barack Obama be friends with someone who bombed the Capitol and is proud of it," the ad says.
The McCain campaign did not put out that ad. It was paid for by one of the top contributers to the infamous 2004 Swift-boat campaign that helped do-in Senator John Kerry's presidential bid.
Obama's campaign has threatened stations that run the Ayers ad and has responded with an ad of its own.
"With all our problems, why is John McCain talking about the 60's, trying to link Barack Obama to radical Bill Ayers? McCain knows Obama denounced Ayers' crimes, committed when Obama was just 8 years old."