Rick Santorum has denied pushing Mitt Romney to take right-wing positions on social issues during the GOP nominating contest, a move many believe cost him the election.

During an appearance on cabler CNN's Piers Morgan Tonight, host Piers Morgan asked Santorum if he had pushed Romney into an “unholy mess.”

“Some people are blaming you for Mitt Romney's failure, and I'll explain to you why before you look aghast in horror,” Morgan said. “Allow me to elaborate. What they're saying is if he hadn't been pushed into fairly right-wing, quite extreme positions as many see them, on social issues in his battle against the likes of you earlier this year for the Republican nominee race, that he wouldn't have got himself into this unholy mess of being branded 'against women,' 'against gay rights,' against all the other social issue hot-button topics that you know about. Do you plead guilty?”

“Mitt Romney, from what I understand, had the positions that he articulated in this election cycle, he had the same positions four years ago,” Santorum answered. “So the idea that somehow I forced him to change his opinion on anything. I'm not aware of any position that Mitt Romney took that was changed as a result of the Republican primary.”

On the issue of gay marriage, Santorum and other GOP candidates opposed to the institution, including Minnesota Representative Michele Bachmann, aggressively accused Romney of advancing marriage equality as governor of Massachusetts.

(Related: Mitt Romney stunned by Rick Santorum claims that Romney advanced gay marriage.)

Santorum added that Romney failed to “vigorously defend the beliefs that he said he espoused and didn't go on the offense.”

“When you're playing defense, which is what I believe the campaign was doing and Republicans were doing generally throughout the course of this campaign, you're not going to win.”