When Newt Gingrich was under attack last week by a pro-Mitt Romney super PAC, he called on his rival to pressure the group to quit running negative ads. Gingrich promised that should a super PAC supporting his presidential run go negative, he would disown it. But now that a pro-Gingrich super PAC is sending Iowans a mailer calling Romney "the second most dangerous man in America" (after President Obama, of course) Gingrich has softened his tone a bit.

"I would encourage them not to do that anymore. I think that's not right, and I don't -- you know, again, I don't control them, but I would discourage them from that kind of negative information. I think that's wrong," Gingrich said on Wednesday of the mailer put out by the Strong America Now super PAC.

What Gingrich might not know is that Strong America Now is finished advertising in Iowa and is preparing to drop similar mailers in South Carolina, PAC founder Mike George told National Journal. He said the PAC is focused on eliminating the national deficit and he believes Gingrich is the anti-deficit candidate with the best chance of winning. Romney's plan to reduce the deficit is not enough, he said.

"We would have never started the super PAC if Romney had signed on to our plan, but he refused," George said. "If he'll just agree to eliminate the deficit, I'll shut the super PAC down."

The PAC spent almost $80,000 on mailers targeting Iowa conservative activists and plans to take a similar approach before South Carolina's Jan. 21 primary, George said.

Asked if running negative ads after Gingrich promised to run a positive campaign would hurt his candidacy, George said, "I sincerely hope not. If that's the case, I'll regret doing it. But based on the success of the negative ads pulling Newt down in Iowa, I don't think we hurt him."

Gingrich's rhetoric has lost some of its fire since last week, when he said that if the pro-Gingrich super PAC Winning Our Future "runs a single negative ad, I will disown the PAC and discourage anybody giving them a penny."