CNBC last week, Giuliani said that a series of gaffes showed that Biden was not very "bright."
"I mean, there’s a real fear if, God forbid, he ever had to be entrusted with the presidency, whether he really has the mental capacity to handle it," the former mayor opined.
On Sunday, CBS host Bob Schieffer seemed shocked by Giuliani's remarks.
"I really said it," Giuliani admitted. "Not knowing what state he was in, not knowing what century he was in within 24 hours, and making what I would consider to be an absolutely disgusting appeal to racial sentiment -- I said, I wonder if he's got the mental capacity to be the president of the United States."
"Is that just campaign talk or do you really think he's nuts?" Schieffer wondered.
"Oh, no, I don't think he's nuts," Giuliani replied. "I'm just saying, I wonder if he's got the kind of balance -- probably what I should have said was, you know, the balance to be president of the United States. This guy is like one gaffe after another. He's a joke on late night television. I think they've also locked him in his room for the rest of the campaign. The president scolded him."
At a campaign event in Virginia last week, Biden had told a group, including many African Americans, that presumptive Republican presidential nominee Mitt Romney's pro-Wall Street policies would “put y’all back in chains.”
"I know that sometimes Republican come across as looking like we feel sorry for ourselves," Giuliani explained on Sunday. "I think we feel if this were [former Vice President Dick] Cheney or [former Alaska Gov.] Sarah Palin or [former Vice President] Dan Quayle, my goodness, all you guys on television would be going crazy about how could he say this and what's wrong with him? So, maybe I was just trying to even up the score a little bit."
"I do think there are some serious questions," he concluded.
Former Republican presidential candidate Rick Santorum also claimed on Sunday that Biden and President Barack Obama were “dividing this country” by playing the race card and using words like “y’all.”