Gingrich has been the target of an avalanche of negative advertising, including TV spots, robocalls and brochures. He has often said in the last few days that he would take the high road. But his anger surfaced Tuesday when he was asked by CNN's Wolf Blitzer what he would like to say to Romney about the attacks.
"All I'd say is, 'Mitt, if you want to run a negative campaign and you want to attack people, at least be man enough to own it.' "
He said Romney was a "moderate Massachusetts governor, who is in fact very timid" with proposals for the economy.
Paul's record, said Gingrich, is one of "systemic avoidance of reality."
Referring to reports about newsletters sent out under Paul's name containing racist and anti-Semitic rants, Gingrich said that the Texas congressman had "a long way to go to explain himself."
Gingrich said he would not vote for Paul for president. When asked whom he would vote for if it came down to a choice between Paul and President Obama, he answered only that Paul could never be the Republican nominee.
Voters, said Gingrich, "will not accept somebody who thinks it's irrelevant if Iran gets a nuclear weapon."
"As a protest, he's a reasonable candidate," said Gingrich. "I don't see how you can engage Ron Paul as the nominee."
Just before Gingrich was interviewed by CNN, he was the keynote speaker at a weekly luncheon of the Rotary Club in Dubuque. A Rotarian asked Gingrich to draw a distinction between himself and Romney, who had mildly tweaked the former House speaker earlier in the day for failing to qualify for the Virginia primary ballot.
In a Facebook post, Gingrich's campaign manager had compared the setback to that suffered by the United States when Pearl Harbor was bombed in 1941. "Obviously, the Virginia setting was not the best hour of his campaign," Romney said in New Hampshire.
At the prompting of a Rotarian, Gingrich recalled President Reagan's admonition against Republicans attacking fellow Republicans.
"I believe in Reagan's 11th commandment," said Gingrich. "I don't want to be invidious about Gov. Romney, who is a very competent manager and a smart man."
But in a conversation with reporters after his speech, foreshadowing his CNN interview, Gingrich was less diplomatic, calling Romney "a Massachusetts moderate [who] raised taxes, created a larger government, imposed greater costs on business... and I think the difference in our records is clear. It's also clear in our policy."
He will try to counteract the extraordinary barrage of attack ads, Gingrich said, by talking to Iowans, making himself available to rebut the attacks in telephone "town halls" and appearances across the state.
But, a reporter noted, there is only a week left.
"We have lots of time, in the age of instant television," Gingrich said. "I trust in the people of Iowa to look at something that's clearly baloney and know that it's baloney."
He issued a challenge to Romney, who, sensing opportunity to fare well in Iowa as Gingrich has slipped in the polls here, left New Hampshire and headed to Iowa today.
"Is he willing to stand up on the same stage--just the two of us--and let's talk about the differences in our policies and our approaches?" Gingrich said.
Gingrich's surge in the polls in the last month has often been attributed to his strong debate performances at a time when many Republicans were seeking a nominee who could be a match for Obama oratorically.
Gingrich plays on that yearning, often saying in speeches that if he becomes the nominee, and Obama refuses to debate him regularly, the White House will become his official scheduler. Wherever Obama goes to give a speech, vowed Gingrich, "four hours later, I will show up. It won't take many weeks of that before he decides a debate will be less painful."
Though Republican voters love to hear him tweak Obama about using a teleprompter -- Gingrich often adds that if he were to debate Obama, he would allow the president to use one "if he wishes" -- his off-the-cuff remarks sometimes land him in hot water.
Recently he said he thought it would be helpful for poor children to acquire the "habit of work" by taking jobs as janitors at their schools. Many poverty experts responded that such labor would stigmatize the poor, but Gingrich insisted Tuesday that his idea had merit.
His own daughter, he said, worked as a janitor at her church when she was 13.
"Getting paid was an educational experience that changed her opinion about the value of money," he said. "We ought to look at schools in New York City where the janitors make more than the teachers. What if you replaced half the janitors with students? ... You could probably employ 12 students for one janitor."
He said when he advanced that idea in Davenport, Iowa, someone in the audience wondered whether janitorial work involves "doing things that aren't pleasant?"
"I said, 'In Iowa, if you ask the farm families what they have kids doing, you will find it's not, quote-unquote, 'pleasant.'"
Gingrich refused to comment on a CNN report that his version of how he came to be divorced from his first wife does not comport with a version in court documents that were stuck away in a drawer in the Georgia courthouse where the couple's dissolution was handled. Gingrich has said that his wife initiated the divorce.
But the court filing found by CNN indicated that his wife, while acknowledging problems, did not want the divorce.
"No," said Gingrich, when asked for a response. "It's 30 years old....That's all I'm going to say."
When Blitzer pressed him about the disparity, Gingrich directed anyone who wants more information to an account written by his daughter, Jackie Cushman. Published by Creators Syndicate last spring, Cushman wrote that her mother requested the divorce.
"Lawyers," said Gingrich, "write a lot of things in the middle of fights."