The lowest point for the man atop the polls came when Michele Bachmann accused Perry of cronyism, suggesting that he forced girls to receive the HPV anticancer vaccine because his former chief of staff was lobbying for the vaccine-maker, Merck, which also "gave thousands of dollars in political donations to the governor."
Perry answered with his trademark boastfulness: "It was a $5,000 contribution that I had received from them. I raise about $30 million. And if you're saying that I can be bought for $5,000, I'm offended."
"Well," Bachmann retorted, "I'm offended for all the little girls and the parents that didn't have a choice." The crowd applauded Bachmann, and Rick Santorum piled on. "This is big government run amok," he informed Perry.
In lieu of a response, Perry served up a platter of platitudes, including "I think we made decisions in Texas" and "There are a lot of different cancers out there."
Bachmann, left for dead after the last Republican debate, returned to incendiary form. Santorum used his minor-candidate perch to peck at Perry. Mitt Romney, refusing to surrender to the man who replaced him as front-runner, got Perry tangled in logic and fact. Even Jon Huntsman, when he wasn't making baffling jokes about Kurt Cobain, told Perry his claim that he couldn't secure the border was "pretty much a treasonous comment."
On the defensive from beginning to end, Perry resorted to the time-honored tradition of making up stuff. When Romney took issue with Perry's previously expressed views that Social Security is a Ponzi scheme, Perry had a comeback: "Governor, you're calling it a criminal - you said if people did it in the private sector it would be called criminal. That's in your book."
The crowd cheered this rejoinder, except that Romney had written no such thing. An electronic search of Romney's book, No Apology, found no use of the word criminal in relation to Social Security. What he wrote was quite the opposite, saying that if bankers raided trusts the way politicians raid the Social Security trust, "they would go to jail."
Perry tried to qualify his previous Ponzi-scheme talk, promising Social Security recipients, "slam-dunk guaranteed, that program is going to be there in place" (even as he argued that Social Security as it was created in the 1930s is "not appropriate for America"). He also dropped his earlier opposition to Medicare prescription-drug coverage.
But mostly, the night was about Perry and the other candidates trying to outdo one another in conservatism. This created some eyebrow-raising results.
There were cheers from the audience of "Yeah!" when the moderator, CNN's Wolf Blitzer, asked if an ill 30-year-old man who had refused to get health insurance should be left to die. There was Ron Paul's explanation of the Sept. 11 attacks as a response to America's "killing hundreds of thousands of Iraqis for 10 years." There was Santorum's accusation that Perry provided education assistance to illegal immigrants "as an attempt to attract the illegal vote - I mean, the Latino voters."
Refreshingly, though, Perry's rivals did not leave his bluster unanswered. Of the increase in jobs in Texas, Romney joked: "If you're dealt four aces, that doesn't make you necessarily a great poker player."
Perry licked his lips. He looked at the ceiling. He blinked so rapidly his eyes could have been sending a coded SOS signal. For a guy who apparently thought he could bluff and bully his way to the nomination, this was much-needed comeuppance.
When Romney pressed Perry about whether he still thought "Social Security should be ended as a federal program, as you did six months ago," the Texan hedged.
"I think we ought to have a conversation," he said.
"We're having that right now, Governor," Romney reminded him. "We're running for president."
Dana Milbank is a Washington Post columnist. E-mail him at email@example.com.