It wasn't long ago that Rick Perry's team were suggesting that he would pull out of some debates -- and after last night's performance, they will be wishing he had.

During last night's CNBC debate, the Republican primary candidate could not remember the name of a government department he was planning to axe. He said: " I will tell you, it is three agencies of government when I get there that are gone. Commerce, Education, and the -- what's the third one there? Let's see."

It was a painfully awkward moment on stage. After a while, his rival Mitt Romney tried to help, suggesting that it might be the EPA (Environment Protection Agency). It wasn't that, so Perry kept struggling on. Eventually he gave up: "I can't. The third one, I can't. Sorry. Oops." When he was answering his next question, he said that he had been "reaching for" the Department of Energy.

Forgetting your own policy is a pretty serious error, and it is difficult to see how Perry -- already way down in the polls -- will recover from this. One person who will be grateful for his gaffe is Herman Cain. The heat was expected to be on him after a string of sexual harrassment allegations, but attention was entirely detracted.