Biden ran for the Democratic presidential nomination in 2008, dropping out after finishing fifth in the Iowa caucuses. He also mounted an unsuccessful bid for the 1988 Democratic nomination.

Biden seemed to call out Rep. Paul RyanPaul Davis RyanRepublicans are avoiding gun talks as election looms The Hill's 12:30 Report Flake to try to force vote on DACA stopgap plan MORE (R-Wis.), Mitt Romney's running mate, on Monday. The vice president, eating Wisconsin cheese soup, said he wanted Ryan to know about his meal.

"I tell you what," Biden said. "I’d like you to know that you could let the congressman [know] I’m eating Wisconsin cheese soup."

Biden has occasionally stirred controversy during the 2012 campaign. In August, he drew fire from Republicans for telling a mixed-race audience that the GOP would "put y'all back in chains" by rolling back President Obama's Wall Street reforms if Democrats lose in November.  

At the time, Obama sought to quell rumors that Biden could be replaced on the Democratic presidential ticket by Secretary of State Hillary ClintonHillary Diane Rodham ClintonWoman behind pro-Trump Facebook page denies being influenced by Russians Trump: CNN, MSNBC 'got scammed' into covering Russian-organized rally Pennsylvania Democrats set to win big with new district map MORE. Obama called Biden an "outstanding" vice president.