The two GOP presidential candidates, who are battling in the establishment lane for Tuesday night's New Hampshire primary, began their exchange with routine attack lines. Christie hit Rubio for being an inexperienced first-term senator, and Rubio returned by bringing up the credit downgrades in New Jersey under Christie's governorship.
But then Christie struck a nerve, ridiculing Rubio's speech style as overly scripted and hollow. 
"See, Marco, the thing is this," Christie said. "When you're president of the United States, when you're a governor of a state, the memorized 30-second speech where you talk about how great America is at the end of it doesn't solve one problem for one person."
Christie contrasted Rubio's Senate speech-making with his own record as a governor who had to solve real problems. 
Rubio returned with an angry attack on Christie's character and integrity.
"Chris, your state got hit with a massive snowstorm two weeks ago; you didn't even want to go back. They had to shame you into going back," Rubio said, until the crowd's booing and whistling almost overwhelmed his voice.
"And then you stayed there for 36 hours, and then you left and came back to campaign."
The argument continued for five minutes, with the five other candidates on stage standing silently by and watching.
"You know what the shame is, Marco," Christie said, toward the end of their exchange. "The shame is that you would actually criticize somebody for showing up to work, plowing the streets, getting the trains to run back on time — when you've never been responsible for that in your entire life."
Rubio interrupted, "You didn't want to go back. … They had to shame him into going back."