"I've seen some awkwardness and some flare-ups that I know should not have occurred," Rangel said, adding that these flare-ups would not have occurred if the Obama campaign hadn't been "messing with the man's wife."
Obama today downplayed any tension with the former president, saying Bill Clinton's terse words of support for him, so far, would not affect party unity, "because I'm going to be appearing with Sen. Clinton, the former president's wife, who was involved in an epic, historic primary with me."
He added that "if the question is, do I want Bill Clinton campaigning for us, for the ticket, leading into November, the answer is absolutely yes. I want him involved. He is a brilliant politician. He was an outstanding president. And so, I want his help, not only in campaigning, but also in governing. And I'm confident that I'll get that help."
Sen. Clinton said of her husband, "he has said he will do whatever he can and whatever he's asked to do."
Beyond Clinton's husband, Obama will want her to urge her supporters -- many of whom are still angry -- to get behind the presumptive Democratic nominee.
According to Rendell, Clinton is "going to deliver a very stern message, in some ways, to her supporters: 'Get over it. Let's go.' As she said, we can't waste any time looking back."
The November election is only 4 1/2 months away. Obama hopes the joint appearance Friday will allow Democrats to stop fighting with each other and to unite against the likely Republican candidate, Sen. John McCain, R-Ariz.
Natalie Gewargis, Jennifer Duck, Andy Fies and Clayton Sandell contributed to this report.