Vice President Joe Biden hit the campaign trail for fellow Democrat Hillary Clinton on Tuesday and slammed Donald Trump's debate performance, saying the Republican nominee is "painfully uniformed."

Biden, who was at Drexel University criticized Trump for calling it "good business" to see the housing market fail. "What in the hell is he talking about,” the vice president said, according to NBC News.

Trump vowed on Tuesday to hit Clinton harder in the next presidential debate after she put him on the defensive by accusing him of being racist, sexist and a tax dodger during their first matchup.

Clinton blasted Trump again the day after a forceful performance in the first of three scheduled debates ahead of the Nov. 8 election. The New York real estate mogul, she said, "was making charges and claims that were demonstrably untrue, offering opinions that I think a lot of people would find offensive and off-putting."

Biden added a jab at Trump on his tax-returns issue before the young crowd at Drexel.

"He acknowledged that he didn't pay taxes because he said… because he's smart; makes him smart," Biden said, referring to an interjection Trump made when Clinton suggested he possibly did not pay federal taxes.

"Tell that to the janitor in here who's paying taxes!"