Rick Santorum Crashes the Rick Perry-Mitt Romney Debate

One of the dark horse candidates finally broke into the Rick Perry-Mitt Romney duel. No surprise -- its Rick Santorum, who has been the most aggressive underdog candidate in previous debates.

Santorum agreed that Perry was soft on immigration. A visibly annoyed Perry fired back, wondering if Santorum had ever been to the border. Santorum responded that he had. Perry continued firing away at Santorum on the issue and defending his record on securing the border.

Santorum also opened a new line of attack against Perry, arguing the Texas governor backed binational insurance. It will be interesting to see if that attack will take off as the campaign continues.