Obama: 'How Do You Know Any President Is Ready?'

"Look, I've lived overseas," said Obama. "I have family overseas. I have served on the Senate Foreign Relations Committee."

As for Clinton's experience in the White House, Obama is dubious. "It is true that I've not lived in the White House," he said. "Although, one of the tough things about Sen. Clinton's campaign has been the degree to which she takes credit for good things that happened and doesn't take credit for bad things that happened."

I Don't Get Rattled'

Obama believes that his "matter of temperament" best prepares him for the White House.

"One of the things that I've known about myself for a long time," he said, "is that, in difficult or stressful moments, I don't get rattled And I don't get rattled during campaigns. I don't get rattled when things are up ... and I don't get too low when things are down."

"Part of the problem that we've seen historically when presidents make bad decisions is either they're ideologically driven — I would argue that that's what happened with George Bush," he said. "Or, oftentimes, it's driven by politics."

But Obama's critics point to Tony Rezko, a Chicago real estate developer, as a reason to question Obama's brand of politics.

Rezko — who has raised a lot of money for Obama over the years — goes on trial this week on corruption charges. Rezko has ties to many politicians, but it is a real estate deal Rezko participated in with Obama in 2005 that enabled the senator to purchase his current home, that has brought a lot of scrutiny to the candidate's campaign.

For Obama, who has called himself a reformer and touted his judgment, some voters might ask how could he enter into this transaction with a longtime contributor who, at that time, was known to be under investigation for corruption?

"I've already said that that was a mistake, even though it was completely above board," said Obama. "Because he had been a contributor, I shouldn't have entered into any real estate transaction with him."

Obama says he has returned all contributions from Rezko or the people associated with him. As for Rezko, he has pleaded not guilty to the corruption charges issued against him.

The Clinton campaign has said that Obama's mea culpa isn't enough and has called on the senator to release more information related to Rezko.