MARSHALLTOWN, Iowa — Republican presidential candidate Newt Gingrich on Sunday returned fire following a steady stream of negative ads from a super PAC backing former Massachusetts governor Mitt Romney.

Hours after he told reporters in Des Moines that Romney “would buy an election, if he could” — a line he later repeated — Gingrich held a news conference here at Junction Sports Bar and Grill. Gingrich — who has pledged to run a positive campaign — said he plans to go after Romney on the air in New Hampshire, but that his ads won’t be “factually false” or “deliberately gotcha” like those of the pro-Romney super PAC Restore Our Future.

“Someone who will lie to you to get to be president,” Gingrich said, “will lie to you when they are president.”

Gingrich said his ads in New Hampshire will point out out that it was the super PAC supporting Romney that took him down in Iowa. He said he will also take aim at aspects of Romney’s record as governor, such as the appointment of liberal judges and the fact that Planned Parenthood was given a role under the Massachusetts health-care law.

View Photo Gallery: Republican candidates kick into high gear ahead of the Jan. 3 Iowa caucuses.

Asked if there was anything he would have done differently in the campaign, Gingrich said he wishes he had fought back against Restore Our Future’s ad hitting him on his financial ties to mortgage giant Freddie Mac with an ad of his own.

The former speaker said he had the flu this weekend, but is now feeling better. Still, he looked tired and was less animated than usual Sunday.

Gingrich said that despite the onslaught of negative ads, he is still a leading GOP contender in Iowa.

“He didn’t get rid of me, he just slowed me down,” Gingrich said of Romney.

He added: “If I had spent $3.5 million defining Romney, he would’ve been at three [percent].”

Gingrich placed fourth in the Des Moines Register poll released Saturday night, with 12 percent.

Asked to respond to Gingrich’s comments, Romney pointed reporters to the nearly $10 million Gingrich announced he had raised in the most recent fundraising quarter.

“He ought to be proud of that,” Romney told reporters Sunday afternoon in Atlantic, Iowa. “We’re working hard to raise funds as well. This is an election, however, that’s not being driven by money raised. It’s being driven by message connection with the voters, debates and experience, and I think that those are the features that are driving the campaign so far and I think they probably will be through the entire process.”

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