Chief correspondent

It was a supremely confident Mitt Romney who hit the campaign trail here Tuesday morning as the newly solidified front-runner for the Republican presidential nomination. His performance in Monday night’s debate poses tough questions for all other current or prospective candidates seeking to derail him next year.

No debate, particularly one in which there were no sharp exchanges or real challenges to the front-runner, can reshape a nomination battle. But Romney’s performance highlighted the reality that, now more than ever, the GOP race has become a question of who will emerge as his strongest rival.

The debate didn’t resolve many of the questions that surround the former Massachusetts governor’s campaign, from the health-care plan he enacted as governor to issues of trust and authenticity. As he put it to reporters Tuesday morning, “I don’t think there are any questions that will be put to rest until somebody’s won.”

Until Romney is put to a real test, first from his rivals and then from voters as they begin to weigh in during next year’s primaries and caucuses, those questions will follow his candidacy. How much has he changed? What has he really learned from his first campaign? Can he generate excitement within his party?

He still can be awkward with voters, but so far this year he has shown more discipline and more comfort as a candidate. That alone isn’t enough, but for now other candidates have more pressing problems to deal with.

Former Minnesota governor Tim Pawlenty hoped to use the debate to establish himself as the clear alternative to Romney. He may yet become that candidate. But he left New Hampshire with fresh doubts about his campaign. His decision to set up a confrontation with Romney over health care on Sunday and then duck it in the debate left other Republicans more than puzzled.

Was his initial decision to attack “Obamneycare” the real mistake? Or was his failure to follow through and confront Romney the more costly error? And how will those Republican donors he needs to attract to his campaign respond over the next two weeks as the deadline for second-quarter fundraising approaches? Pawlenty’s poll numbers have not moved much this year, which is not surprising. But a weak fundraising report could raise further concerns about his strength and appeal.

Pawlenty left New Hampshire with another problem, and another strategic choice. The strong performance by Rep. Michele Bachmann (Minn.) — the only other clear winner Monday night — complicates Pawlenty’s situation in Iowa.

Bachmann showed stage presence and a flair for attracting attention to herself. She lacks the experience of Pawlenty, a two-term former governor, but she could become a real force in Iowa, the state Pawlenty knows he must win to be Romney’s chief challenger next year.

Pawlenty’s first task is to make sure he finishes ahead of Bachmann in the Iowa straw poll in August. That could cost him $1 million or more in precious campaign funds (Romney spent more than $2 million to win the straw poll four years ago). The last thing he needs is for Bachmann to come out of the straw poll with fresh momentum. Whatever her staying power, she can make life terribly difficult for her fellow Minnesotan.

Bachmann’s debate performance was just that, a good showing in a single event. For her, the question is what she does with it. She has shown in recent weeks that she is serious about trying to run a good campaign, but so much depends on how she handles herself. Herman Cain learned Monday night that one good debate, which he had in South Carolina, doesn’t begat a second. Bachmann has raised expectations for herself and now has to meet them or risk falling back.

Monday’s debate also highlighted more clearly the choices that face two prospective candidates, Sarah Palin and Texas Gov. Rick Perry. No one can predict what kind of staying power Bachmann might have, but her emergence as the likely favorite of many tea party voters and social conservatives could accelerate Palin’s timetable.

She and Palin are now on a collision course, unless the former Alaska governor and vice presidential nominee has no real interest in running. But if Palin is truly thinking about joining the race, she might need to announce it earlier than late August. Her next bus tour becomes all the more interesting.

Perry, too, will have to factor in the competition from Bachmann for tea party support. Those around him believe his appeal is not limited to one segment of the conservative coalition — that with the record of job creation in Texas he can challenge Romney on the campaign’s most important issue. He also has far more experience, given his decade as governor, to offer voters. But if Bachmann can peel away part of the base that otherwise might naturally be his, Perry’s path becomes that much more difficult.

The extent to which Romney solidified his position on Monday will also affect Jon Huntsman Jr. The former Utah governor and former U.S. ambassador to China in the Obama administration will announce his candidacy next week.

In so many ways he and Romney are competing for the same support. Both are former governors, both tout business experience, both are Mormons, and neither feels comfortable with the electorate in Iowa and therefore must take his stand in New Hampshire.

The rest of the Republican field will struggle for attention. Former House speaker Newt Gingrich has a campaign in deep trouble. Former senator Rick Santorum (Pa.) was overshadowed. Rep. Ron Paul (R-Tex.) has his followers but not much more. Cain also has some support but will have more trouble expanding it after Monday.

Romney might not be the strongest of front-runners, but he is likely to strengthen his position by winning the second test of the campaign: the second-quarter fundraising reports. By all indications, he will lead the field, possibly by a big margin.

That leaves Romney versus the field. Until this week, many of the questions about the GOP race have been about the former governor. Though he is right that it will take time for them to be put to rest, there are now just as many questions about his rivals. That is an enviable position for Mitt Romney as the summer arrives.