"You've got conservative whites here, and I think there are some whites who are probably not ready to vote for an African-American candidate," Rendell told the editorial board of the Pittsburgh Post-Gazette in remarks that appeared in Tuesday's paper.
To buttress his point, Rendell cited his 2006 re-election campaign, in which he defeated Republican challenger Lynn Swann, the former Pittsburgh Steelers star, by a margin of more than 60 percent to less than 40 percent.
"I believe, looking at the returns in my election, that had Lynn Swann been the identical candidate that he was - well-spoken, charismatic, good-looking - but white instead of black, instead of winning by 22 points, I would have won by 17 or so," he said. "And that (attitude) exists. But on the other hand, that is counterbalanced by Obama's ability to bring new voters into the electoral pool."
Rendell, chairman of the Democratic National Committee in 2000 and previously Philadelphia's mayor, endorsed Clinton on Jan. 23.
Pennsylvania holds its primary April 22.
Several figures in Clinton's campaign, including her husband, the former president, have been criticized in recent weeks for raising Obama's race. In response, Bill Clinton has said he will stick to promoting his wife, rather than defending her.
Later Tuesday, Rendell's spokesman said the governor did not mean to offend anyone.
"He was simply making an observation about the unfortunate nature of some parts of American society," said spokesman Chuck Ardo. "He wasn't being critical, he wasn't making accusations, but just being realistic."
