As presidential running mates in 2012, Mitt Romney and Rep. Paul Ryan were occupationally required to agree on nearly everything.

But they stumbled onto one area of disagreement Thursday: Who would make a better president?

After Fox News' Megyn Kelly posed the question to the duo, Ryan quickly pointed to Romney. "I'll give it to him," Ryan said.

"It's his turn now," Romney countered. "I've had my go-around."

Romney and Ryan spoke with Kelly from Chicago, where they reunited to promote Ryan's new book, "The Way Forward: Renewing The American Idea."

Both Romney and Ryan have been mentioned by Republicans as potential presidential contenders, but each has cast doubt upon his ambitions.

Romney has said he does not intend to run for a third time. Ryan, meanwhile, has said he has not reached a decision; however, he is thought to have his eye on chairing the House Ways and Means Committee during the next Congress.