The chairman of the Republican Party of Pennsylvania Monday called Democratic presidential nominee Barack Obama "a terrorist's best friend."

In a press release posted on the party Web site -- headlined "PAGOP: Obama -- A Terrorist's Best Friend" -- Robert A. Gleason Jr. said Obama's relationship with William Ayers, a University of Illinois-Chicago professor and former 1960s militant, "is alarming and absolutely needs to be questioned."

"We are electing someone to be our next Commander-in-Chief and I think it is more than fair to look into their background," Gleason said, echoing a theme that the campaign of Republican presidential nominee John McCain has been hammering since Saturday.

Gleason said the Obama campaign has "admitted that Obama and Ayers were 'certainly friendly' and that says a lot about Barack Obama's character."

"What does it say about the character of Barack Obama that he knowingly associates with terrorists?" Gleason said. "It tells me that Obama lacks the judgment and character to be our next Commander-in-Chief."

Obama's campaign has denied that Obama and Ayers were ever close and has called the McCain campaign's assertions "offensive."

Pennsylvania is shaping up as a potential battleground state in the November election.