Transcript for Joe Biden tries to laugh off scrutiny over string of misstatements
and CVS, as well as Wegman's following that move. Former vice president Joe Biden, the democratic front-runner, and that means, of course, growing scrutiny. Tonight, Biden on his own gaffes. Stephen Colbert asking Biden, "Are you going nuts?" How Biden answered. Here's Mary Bruce. Reporter: After a string of misstatements, the self-proclaimed gaffe machine went on late night television and tried to laugh off the scrutiny. In the last few weeks you've confused New Hampshire for Vermont, said Bobby Kennedy and mlk were assassinated in the late '70s. Assured us, "I'm not going nuts." Follow-up question, "Are you going nuts?" Look, the reason I came on the "Jimmy Kimmel show" is because I'm not. I mean, I -- I -- I -- I'm not. Reporter: Pressed again, Joe Biden downplayed his missteps. Any gaffe that I have made, and I've made gaffes, like every politician I know has, have been not about a substantive issue. Reporter: And he pushed back on a "Washington post" report that he's been telling inaccurate stories out on the campaign trail, saying it's the message that matters, not the details. I'm not sure that's relevant, but I don't -- you know, I don't get wrong things, like, Y know, we should lock kids up in cages at the border. Reporter: The early front-runner joking that he's already considering his running Have you asked Michelle Obama for advice? Only to be my vice president. I'm only joking! Michelle, I'm joking. Reporter: Now, Biden is arguing that his gaffes are largely trivial, but he is also facing a lot of criticism for saying recently that, quote, the details are irrelevant in terms of decision-making. David? Mary Bruce live in Washington. Mary, thank you.
This transcript has been automatically generated and may not be 100% accurate.