"I think Barack Obama is very destructive to the future of the United States. I think Ron Paul's views are totally outside the mainstream of virtually every decent American," Gingrich said Tuesday in a CNN interview with Wolf Blitzer.

Could he vote for Paul? "No." If it came down to Paul vs. Obama? "You'd have a very hard choice at that point."

Gingrich's fencing with Mitt Romney seems like an afternoon at a gentleman's club compared with his slams on Paul. "As people get to know more about Ron Paul, who disowns 10 years of his own newsletter, says he didn't really realize what was in it, had no idea what he was making money off of, had no idea that it was racist, anti-Semitic, called for the destruction of Israel, talked about a race war - all of this is a sudden shock to Ron Paul?" he asked. "There will come a morning people won't take him as a serious person."

Right now in Iowa, the week before the state's Jan. 3 caucuses, Paul is a very serious person - in the top tier along with Gingrich and Romney and playing aggressively to win. "If Dr. Paul will have to soldier on without Newt's vote, then so be it," Paul campaign manager Jesse Benton said in a statement. He called Gingrich "a divisive, big-government liberal who is unelectable" and his attack on Paul a "childish outburst."