"I've got to admit, these folks are shameless," Obama told a rally here, displaying a passion and an intensity rarely seen from the Illinois senator.

He noted that Palin had originally supported an infamous "Bridge to Nowhere" project in Alaska, and had hired a Washington lobbyist to secure millions of dollars in federal funding for the small town of which she was mayor.

"When John McCain gets up there with Sarah Palin and says 'we're for change'... you've got to ask yourselves, what are they talking about, how do they have the nerve to say it?" the Democrat added.

"It's empty words. You're just saying it because you realize, gosh, Obama's been talking about change and it seems to be working, so maybe we should say it too," he added to mocking laughter from a crowd of 1,500.