Susan Castner, a Clinton delegate from Portland, Ore., said she sees some of Clinton's qualities in Biden. She likes his experience, especially on foreign policy.
"It really kind of humanizes Barack Obama," Castner said. "He has this air of perfection, and Joe Biden is more down to earth."
"I love his passion," Castner said of Biden. "I like him a lot."
Obama announced Saturday that Biden, a senator from Delaware for the past 36 years, would be his running mate, passing over Clinton, Kansas Gov. Kathleen Sebelius, Virginia Gov. Tim Kaine and Indiana Sen. Evan Bayh.
Clinton issued a statement Saturday praising Obama's decision and calling Biden "an exceptionally strong, experienced leader and devoted public servant."
Some of her supporters were less charitable.
"It's a total diss to Sen. Clinton, in my opinion," said Diane Mantouvalos, co-founder of the Just Say No Deal Coalition. "It just speaks volumes about how Barack Obama doesn't stand for anything."
Mantouvalos, of Miami, is part of an Internet movement of Clinton supporters who refuse to back Obama, regardless of pleas from Clinton herself. Mantouvalos is in Denver, where the Democratic National Convention is scheduled to start Monday, stoking anti-Obama sentiment.
She said the selection of a Washington insider undermines Obama's call for change.
"It was a desperate move," Mantouvalos said.
John West, a Clinton volunteer during the primaries, said he's not excited about Biden, but he had little hope that Clinton would get the nod.
"Most people feel that if she wanted to press to be vice president, she would have made a bigger push for it," said West, of Chicago.
West has been working with Clinton delegates to have her name placed in nomination at the convention, with a roll call vote - a vote that was agreed to by both Obama and Clinton.