Obama offered his remark to in an interview with ABC News on the eve of Thursday night's vice presidential debate.
Biden has been a controversial figure, occasionally prone to making rhetorical gaffes. Obama himself came under withering criticism for his lackluster performance in last week's debate against Republican challenger Mitt Romney.
Biden, who served Delaware in the U.S. Senate for several terms before becoming vice president, got into a rough patch recently when he told a campaign audience in Charlotte, N.C., that the middle-class in America has been "buried" the last four years -- the same time frame of Obama's first term as president.
