From an AP brief (can't find the link):
The Delaware Democrat, who trails badly in the polls in advance of the Jan. 3 Iowa caucuses, made his comments after a supporter, J.R. Ackley, urged him to "take on" the three front-runners in the race.
"It's like three witches sitting around arguing about who's ugliest," Ackley said of Clinton, Obama and Edwards, whom he said lacked the experience that Biden has.
"I admit I've been reluctant," Biden said.
He said Clinton "has done really good work" for 35 years helping children. "But I was actually writing the laws and getting things changed."
Biden called Obama a "great guy," then said, "I spent time in the projects" and was a public defender.