A day in the life of a candidate under intense pressure takes many turns. One moment, Senator Clinton compared herself to Margaret Thatcher, Britain’s “Iron Lady” and a direct descendant of fearless woman warriors Boudica and Elizabeth I. The next, in the Café Espresso in Portsmouth, N.H., she choked back tears as she pondered losing today’s New Hampshire primary. The two very different faces of Mrs. Clinton, one determined and defiant, the other wistful and vulnerable, left voters wondering whether the incessant strain of the increasingly rough Democratic campaign is genuinely getting under her skin, or whether it was a cynical ruse to grab the headlines and rustle up some sympathy on the morning the Granite State votes.

What was not in doubt was that Mrs. Clinton succeeded in catching the press’s attention. For once, since the upset in Iowa left her languishing in third place, the story was all about her. And, while she lingered damp-eyed in the limelight, she set off a few rockets in Senator Obama’s direction.

Until yesterday, it has been Republicans who have invited comparison with Baroness Thatcher, in the hope that some of the magic of conservatism’s golden age may brush off on them. Lady Thatcher, 82, is too canny to endorse foreign politicians, but she graciously welcomes those who make a pilgrimage to her door.

The steely Mrs. Clinton paid the “Iron Lady” a rare compliment yesterday, paying tribute to her early action on climate change. “Guess who stepped to the plate in 1990? Margaret Thatcher,” the senator said, adding that, like her, Lady Thatcher “happens to be a woman.”

Mrs. Clinton then invited voters to make further comparisons. “We had one leader — I don’t know how likable she was — we had one leader who made it a priority and got the job done,” Mrs. Clinton said, a reference to the fact that, although respected and revered, Lady Thatcher was rarely liked in her own country.

When asked in the debate on Saturday about her dislikability, Mrs. Clinton elicited a rare moment of sympathy by saying, “You have hurt my feelings.” Mr. Obama’s graceless response, “You are likable enough, Hillary,” was a low point in his otherwise well-mannered campaign.

Likability was a theme developed on Sunday night by President Clinton, who reflected on how he and his wife are stuck being who they are. “There’s nothing we can do. I can’t make her younger, taller, male,” he said, to laughter.

If Mrs. Clinton cannot make herself likable, her campaign has encouraged her to appear softer, more sympathetic, so her weepy response to women in a coffee shop came right on cue.

Asked whether she found the campaign grueling, she said yes, it was. “It’s not easy. And I couldn’t do it if I just didn’t, you know, passionately believe it was the right thing to do,” she said. Then, with a catch in her voice, she continued, “I’ve so many opportunities from this country, I just don’t want to see us fall backwards,” her usual brazen delivery slowing to a halt.

“So,” she started, her eyes glassy with emotion, “you know, this is very personal for me. It’s not just political. It’s not just public. I see what’s happening, and we have to reverse it. And some people think elections are a game. They think it’s like who’s up or who’s down. It’s about our country. It’s about our kids’ futures. It’s really about all of us together.”

In full control, as the women around her applauded their support for a sister appearing in distress, she milked the moment.

“Some of us put ourselves out there and do this against some pretty difficult odds,” she said. “And we do it, each one of us, because we care about our country. But some of us are right, and some of us are wrong. Some of us are ready, and some of us are not. Some of us know what we will do on Day 1, and some of us haven’t thought that through enough.

“And so, when we look at the array of problems we have and the potential for it getting, really spinning out of control, this is one of the most important elections America’s ever faced.

“So as tired as I am — and I am — and as difficult as it is to kind of keep up with what I try to do on the road, like occasionally exercise, and try to eat right — it’s tough when the easiest food is pizza — I just believe so strongly in who we are as a nation, so I’m going to do everything I can to make my case and, you know, then the voters get to decide.”

Whether a genuine moment of candor or a carefully contrived piece of political theater, Mrs. Clinton’s maudlin interlude switched the direction of the campaign last night, leaving pundits divided over the authenticity of the incident and wondering whether the Clintons had once again manufactured a last-minute episode of high drama with which to trounce their opponents.

Senator Edwards, for one, remained unmoved. “I think what we need in a commander in chief is strength and resolve, and presidential campaigns are tough business, but being president of the United States is also tough business,” he told reporters in Laconia, N.H.

In one respect at least, Mrs. Clinton’s comparison with Lady Thatcher is inapt. Throughout the direst moments of her premiership, including the sinking of British ships during the Falklands War, and when she survived an assassination attempt by Irish Republicans, she only wept twice in public.

The first was when her aberrant son Mark was lost in the Sahara, believed dead, during a car rally, the second when she was brutally deposed by her Cabinet and set off to Buckingham Palace to tender her resignation to Queen Elizabeth.

Both lapses were unexpected, out of character, and unrehearsed.

Mr. Wapshott’s “Ronald Reagan and Margaret Thatcher: A Political Marriage” is published by Sentinel.