Businessman Herman Cain walked into tonight's CNN Republican Presidential debate as one of the two front-runners, he hobbled out bloodied and fighting for air.

In the first 10 minutes of the debate, all six other candidates ganged up on Cain over his 9-9-9 plan, criticizing it as an overly-simplistic response to a complicated problem that would result in a tax increase for many Americans.

"Herman, I love you brother, but let me tell you something — you don't have to have a big analysis to figure this thing out," Texas Gov. Rick Perry said. Go to New Hampshire where they don't have a sale tax and you're fixing to give them one. They're not interested in 9-9-9."

Mitt Romney, who ties Cain in national polls, turned around Cain's claim that state taxes and the 9-9-9 plan are "apples and oranges," drawing cheers when he said "I'm going to get a bushel basket that has apples and oranges in it because I'm going to pay both taxes, and the people in Nevada don't want to pay both taxes."

Cain flailed under the pressure, with his only defense that his opponents' — and independent analysts — got their facts wrong, and directed people to his website for his campaign's analysis.

He also faced criticism for saying he would trade all of the U.S. government's prisoners at Guantanamo Bay for the life of one U.S. solider — before walking it back later, saying he "spoke in error — I would never negotiate with terrorists."

It was not Cain's first foreign policy slip-up this week, after he admitted on Meet the Press that he is unfamiliar with the neo-conservative movement.

Cain was the anti-Romney candidate going into this debate, but it appears Texas Gov. Rick Perry is poised to retake that position at the expense of Cain. Tuesday night's debate proved once and for all that the Cain honeymoon is over — and he seemed unable to withstand the scrutiny given to a top-tier candidate.

For Cain, it's all downhill from here.

Watch Cain struggle to defend his 9-9-9 plan:

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