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Associated Press
Presidential candidate Newt Gingrich is surrounded by supporters at a Virginia GOP fundraiser on Thursday.

BETHLEHEM, N.H. — Mitt Romney, seemingly happy with how the Republican presidential campaign is playing out, is not explaining or apologizing for TV attack ads paid for by his allies that have damaged his chief rival's political standing 12 days before the Iowa caucuses.

Whether he's the true front-runner or not, Romney is acting like one. He refuses to be dragged into debates about the campaign's tone, high-stakes brinkmanship in Congress over a payroll tax dispute — or into a one-on-one debate sought by Newt Gingrich.

The former Massachusetts governor on Thursday shrugged off Gingrich's complaints about the ads and Romney's reluctance to weigh in on the political standoff over extending payroll tax cuts, which lawmakers late in the day appeared to be resolving just in time to head off a hit on workers' paychecks Jan. 1.

Gingrich, the former House speaker, has repeatedly called on Romney to face him before cameras and defend the ads, which are largely financed by a heavily bankrolled group friendly to Romney.

"We've had many occasions to debate together, and we'll have more, I presume quite a few more, before this is finished," Romney told The Associated Press. "But I'm not going to narrow this down to a two-person race while there are still a number of other candidates that are viable."

Some party insiders expect a strong showing in the lead-off Iowa caucuses Jan. 3 by libertarian-leaning Rep. Ron Paul of Texas. But they generally see Gingrich, a prominent GOP figure for more than 30 years, as having the best chance to compete with Romney for weeks or months.

Gingrich and Romney planned to campaign through Friday, underscoring the stakes for both candidates even as the pace by the crowded field began to lighten for Christmas weekend. The barrage of ads, though, kept up in Iowa and New Hampshire.

In a sign of his late organizing start, Gingrich spent Thursday in Virginia, scrambling to secure the 10,000 voter signatures he needs to get on the state's March 6 primary ballot. It cost him a precious day of campaigning in Iowa and in New Hampshire, which holds its primary Jan. 10.

Texas Gov. Rick Perry has been by far the heaviest spender in Iowa. However, his campaign this week gave 30-day termination notices to all political consultants in Iowa, New Hampshire and South Carolina. Aides said the campaign was moving toward fiscal discipline as it prepares for a long multistate strategy.

But even in states that vote early, political consultants rarely receive such notices. Some are usually retained with an eye toward the general election, or sent to other states.

Gingrich renewed his call for Romney to condemn or defend ads sponsored in Iowa by a so-called super PAC. It's run by Romney supporters who are legally barred from coordinating with the official campaign.

Romney, interviewed during his bus tour of New Hampshire, didn't take the bait.

"Could I come out and speak about ads, generally, and speak about positive ads and negative ads?" Romney asked. "Of course, that's available to everybody. But I'm not in any way coordinating the ads or the approach that's taken by the super PAC."