(Image Credit: Jae C. Hong/AP Photo)

PHOENIX - Mitt Romney, debuting a new line of attack,  seized on GOP challenger Rick Santorum's admission during  Wednesday's night's debate that  Santorum had voted "against his principles" during his tenure in Washington. 

"Now who watched the debate last night? It was kind of fun. I enjoyed it," said Romney in a speech to the Associated Builders and Contractors National Board Meeting Biltmore Hotel in Phoenix. "It was kind of an interesting night. I didn't expect what happened. What happened was we saw in this case Sen. Santorum explain most of the night why he did or voted for things he disagreed with.

"You know I don't know if I've ever seen a politician explain in so many ways why it was he voted against his principles," said Romney. "I can tell you one thing if I'm president of the United States I will abide by my principles and my team will be the people of the United States of America.

"And he talked about this as being taking one for the team. I wonder which team he was taking it for," said Romney, sparking laughter from the crowd gathered in a hotel ballroom. "My team is the American people, not the insiders in Washington, and I'll fight for the people of America.

During Wednesday night's CNN debate in Mesa, Ariz., Santorum said supporting "No Child Left Behind" was "against the principles" he believed in.

"I have to admit, I voted for that," said Santorum. "It was against the principles I believed in, but, you know, when you're part of the team, sometimes you take one for the team, for the leader, and I made a mistake," said Santorum. "You know, politics is a team sport, folks. And sometimes you've got to rally together and do something."

Romney, who spoke at what is expected to be his final event in Arizona before the state's primary on Tuesday, continued  his efforts to paint Santorum as a "Washington insider."

"He explained, for instance, why it was he voted against for the repeal of right to work laws, again, saying that was against his principle, but he did it for the team," said Romney. "He explained why he voted to protect Davis-Bacon. He explained why he voted to raise the debt ceiling five times without compensating cuts in federal spending. He explained why it was he voted to fund Planned Parenthood, even though that was against his principles. He explained why he voted for No Child Left Behind even though that was against his principles. He explained why he voted for the Bridge to Nowhere even though that was against his principles."