Mitt Romney said Monday that CNN's Candy Crowley overstepped her bounds by playing fact-checker during a debate between Romney and President Obama in 2012.

Appearing on Hugh Hewitt's radio show, Romney said Crowley shouldn't have interjected to confirm President Obama's claim about the evolution of the administration's talking points about the terrorist attack in Benghazi, Libya.

"Well, I don’t think it’s the role of the moderator in a debate to insert themselves into the debate and to declare a winner or a loser on a particular point," Romney said. "And I must admit that, at that stage, I was getting a little upset at Candy, because in a prior setting where I was to have had the last word, she decided that Barack Obama was to get the last word despite the rules that we had."

Republicans were highly critical of Crowley for her decision to confirm Obama's claim that he had described the attack in Benghazi as a terrorist attack the day after it occurred. While Obama referred broadly to "acts of terror" during a Rose Garden address, the administration didn't include terrorism in its talking points in the days afterward.

Romney added: "So, she obviously thought it was her job to play a more active role in the debate than was agreed upon by the two candidates, and I thought her jumping into the interaction I was having with the president was also a mistake on her part and one I would have preferred to carry out between the two of us, because I was prepared to go after him for misrepresenting to the American people that -- the nature of the attack."

Romney declined to say whether he thought the administration was deliberately covering up the true origins of the attack.

CNN did not immediately respond to a request for comment.