In their first joint appearance together, Biden went right at Republican candidate Sen. John McCain (Ariz.). While he called him a friend, Biden warned that “the harsh truth” is that McCain would offer four more years of Bush administration policies.

Sen. Obama (Ill.), standing at the old State Capitol in Springfield, Ill., introduced Biden as “one of the finest public servants of our time,” and highlighted the Delaware senator’s past tragedies and legislative record.

Biden said that while he and Obama “come from very different places, we share a common story, an American story.”

While Biden does bring foreign policy experience to the Democratic ticket, the two candidates focused their remarks on the economy, with the new vice presidential pick joining in the recent Democratic strategy of slamming McCain for flubbing a question about how many homes he owns.

The Delaware senator, while talking about families who sit around their kitchen tables figuring out how to make ends meet, said McCain doesn’t have that problem.

“He’ll have to figure out which of seven kitchen tables to sit at,” Biden said.

Karl Rove, Bush's former strategist and a commentator for Fox News, said after the speeches that Biden quickly embraced the attack dog role “and he did it with a smile as he took the knife and shoved it into his friend John McCain.”

The two candidates are breaking with tradition as they will go their separate ways in the lead-up to the convention. Obama is set to visit several swing states en route to Denver while Biden is said to be heading there shortly.