Vice President Joe Biden originally turned down then presidential candidate Barack Obama's request to be his running mate, Biden said last night.

"I initially said no, that I wasn't interested," Biden said at a Democratic fundraising dinner in Pittsburgh. "He asked me to think about it."

Biden said he eventually accepted the offer "a couple months later."

The now-VP apparently wanted reassurance that Obama was really committed to fundamental change.

"Are you really committed to changing the course of this country?" Biden says he asked Obama. "He reached out, shook my hand, and said, 'I am.'"

Jill Biden once mentioned on air that her husband had a choice between being secretary of state or vice president. Biden's office denied that claim.