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 today, 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.