Biden said that Obama's campaign would be "vastly outspent by super-PACs" favoring the GOP. Republican super-PACs have thus far out-raised their Democratic counterparts over the campaign season.

"Folks, we're not going to be able to match that," Biden said.

Biden said Obama's campaign would be able to counter the massive spending through a serious ground operation, adding that "you're going to see organizers" in Arizona.

In praising Obama, Biden said he's made decisions that weren't always popular, such as the Wall Street bailout which, Biden said, was "like legalizing rattlesnakes in the lobbies of hotels in Arizona."

"That's why I love this guy," Biden said of Obama.