Alternate possibility: He was just trying to call Obama a niggard, "a stingy or ungenerous person." Not realizing how this would backfire until it was too late.
I'm 99% sure he was reading from a teleprompter. He glaces away from the teleprompter right before his slip up and somehow manages to get right back into his speech mid-sentence. If he was speaking extemporaneously he would have caught himself, possibly repeated the word or started the sentence over, he wouldn't have dived right into the middle of his next sentence. We should ask the Santorum camp for the transcript so we can find out what he was supposed to say.