"Undecided people are having a difficult time just culturally making the change, making the move for the first African American president in the history of the United States of America," the Democratic vice-presidential nominee said at a San Francisco fundraiser Saturday evening. "So we need to respond. We need to respond at the moment, immediately, not wait, not hang around, not assume any of this won't stick."

"You see these vicious attacks on Barack's character," Biden told supporters. "I mean, this is dangerous stuff these guys are doing. This stuff is on the edge. It's on the edge. You know, there's some folks out there in the community nationwide that aren't as stable as others. It's a very small minority. But having these rallies where people are showing up saying, you know, the things they're saying - I don't even want to repeat them -- it's not a healthy thing."

Biden cited automated GOP calls describing Obama as having "worked closely" with "domestic terrorist Bill Ayers", Virginia Republican Party chairman Jeff Frederick telling volunteers to tie Obama to Osama bin Laden, and speakers at Republican rallies referring to Barack Hussein Obama.

I got started in the civil rights movement as a young kid in a state that had been segregated by law with the eighth largest black population in America, as a percent of population," Biden said. "And I never thought, but I prayed I'd live to see the day, when -- and I never thought I could be part of it - a part of seeing to it that we for the first and significant, fundamentally significant way, put a lot of that past behind us and began to unite the nation."