Speaking with Candy Crowley on CNN's "State of the Union," Giuliani, a former GOP presidential candidate himself, was invited to walk back critical statements he made about Romney going back to 2008. Instead, Giuliani ended up reaffirming some of them, as he unfavorably compared Romney's stint as governor of Massachusetts to his own years as New York City's mayor.

"Maybe it was circumstances or whatever, but I had massive reduction in unemployment," Giuliani said. "He had a reduction in unemployment of about 8 percent, 10 percent -- I think it was 15 percent. I had a reduction in unemployment of 50 percent. They had a growth of jobs of 40,000. We had a growth of jobs of 500,000. So I was comparing what I thought was my far superior record to his otherwise decent record, but the numbers weren't as great."