"You're not ruling that scenario out?" Cavuto asked.
"C'mon Neil, I'm not that nominee," Romney replied. "I'm not going to run for office. I'm going to support whoever our nominee is."
Romney called the odds of him even being asked to step up in the event of a contested convention "a zero percent chance."
"They're not coming to you and they're not coming to me," Romney told Cavuto.
"If they did?" Cavuto asked over him.
"I'm not going there," Romney said.
Romney insisted the eventual GOP nominee "would be someone running for president" and said he'd support that nominee. As Cavuto continued to grill him, Romney repeated that he thought the odds other GOP leaders would call on him to be the nominee were "one in 10 million."
"What happens if President Obama steps aside and says 'Mitt, I'm really in trouble and Joe Biden is sick, would you come in and be president?' It's not gonna happen," Romney said.
"I think my scenario would be more likely than that one," Cavuto retorted.