MANCHESTER, N.H. – Camille Brown, a married working mom with two daughters, is one of the most sought-after people in the state – a sure-to-vote, undecided woman. But to talk to her, it's not a good feeling at all.

In earlier contests, she had always been so sure-footed about her candidate and even volunteered at the campaign. And now, with only three days left before the historically important New Hampshire primary, she is still checking the issues and her gut, but finds herself near the deadline still tiptoeing around a decision.

"I am agonizing between Barack Obama and Hillary Clinton," said Ms. Brown of Nashua.

On Tuesday, women are expected to make up 56 percent of primary voters – they were 57 percent of the Iowa caucus-goers – and as the largest voting constituency, they hold the key to not just a New Hampshire victory, but potentially the future fate of even the top campaigns. Republicans Mitt Romney and John McCain and Democrats Mrs. Clinton and Mr. Obama find themselves in virtual dead heats in the Granite State.

All of the candidates are reaching out to women, but especially the Democrats. They have hosted coffees and forums, sent out their spouses and targeted women voters with postcards and e-mail efforts.

Women were once considered a natural constituency for Mrs. Clinton, but in Iowa, 35 percent of women who caucused stood for Mr. Obama, compared with 30 percent who backed Mrs. Clinton. Those results, in particular, have turned the New Hampshire race on its earring.

And Mrs. Clinton's campaign has stood up and taken notice, adjusting its strategy to put less focus on older women and reach out more to younger women.

To shore up support among women and win over the undecideds, both senators have sent out New Hampshire-elected female officeholders as surrogates to speak to women about health care and education issues.

And Mrs. Clinton in particular has databases, top campaign officials and state workers dedicated to maintaining what as recently as two weeks ago was a strong edge among women: Mrs. Clinton had the support of 39 percent of likely Democratic women, compared with 28 percent for Mr. Obama and 15 percent for John Edwards.

"It seems everything is really up for grabs," said Meredith Wagner, public affairs vice president of Lifetime Networks, which has been spearheading "Every Woman Counts," an effort to increase voting and attention to women's issues.

But one thing is sure: "Women are going to be the deciders in New Hampshire and probably in the nation," Ms. Wagner said.

Andrew E. Smith, a political science professor and pollster at the University of New Hampshire, said Mr. Obama and Mrs. Clinton in particular have been targeting women, but she has been aiming at working women and he has been winning the upscale, college-educated woman.

"In New Hampshire, you have to win by a ground campaign and organization. They have a list of all the people who have voted in past primaries; they know the characteristics of their home down to the kind of magazines they take," Dr. Smith said.

Once they identify supporters, there is a push to have them e-mail and call their friends to widen the circle. It's also not hard to push them to the polls – more than 70 percent of eligible voters cast ballots in the New Hampshire primary.

Dr. Smith said his polling has seen that those with the most education and younger women in particular are drawn to a message of new direction and change, "and that's going to be Obama," he said.

"Clinton has made a conscious effort to go for working women. That's one of the reasons she's looking at health care and drilling down on that issue. These women might not have health insurance, and they might be trying to balance children and their jobs," he said.

Ann Lewis, a senior adviser to Mrs. Clinton, said the campaign has learned from Iowa that its targeting did not include enough young people and it is trying to retool that. Mrs. Clinton's appearances now include high schools and universities.

She also is touting support from notable women around the state, including New Hampshire's House speaker and Senate leader, who are campaigning around the Granite State.

Ms. Lewis also said they are still emphasizing the experience of their candidate. "She is ready to be president – that is terribly important," she said.

And after 35 years as an activist, and an advocate for children and women, "you know what she will do because you know what she has done," Ms. Lewis said.

Carol Shea-Porter is the first female congresswoman for New Hampshire, elected just two years ago, and she has been traveling the state stumping for Mr. Obama.

"Hillary is a very good person," Ms. Shea-Porter said. But the family she grew up in was Republican, and she believes Mr. Obama can bring both sides together.

"Voters are not apathetic. They're disengaged. And he's infusing people with hope," she said.

Betsy Myers, who is now the Obama campaign's chief financial officer but served formerly as President Bill Clinton's director of women's initiatives and outreach, said the campaign is continuing the same strategy it employed successfully in Iowa.

"Our campaign has always been inclusive," Ms. Myers said, employing house parties, surrogate speakers and rallies to reach out to as many people as possible.

Sharon Sykas, past president of the National Federation of Republican Women in New Hampshire, said that women's issues also include tax policies and security – points that are lost on the Democratic candidates who advocate more government spending and immediate withdrawal from Iraq.

The Iraq war is important to Republican women who recognize that its stabilization is vital to America's security, she said.

"Women are the majority of small-business owners," Ms. Sykas said, and they worry about mandates on health care and changes in tax policies. "They believe in smaller government to give us the money locally and in letting us settle upon our own options in health care," she said.

And then there is Mrs. Clinton. "She's polarizing. And she's going to drag people out on both sides," said Ms. Sykas, a Romney supporter.

All this is fodder for the undecided Ms. Brown.

"I know she's a hard-working woman who's very smart," she said of Mrs. Clinton, but while Ms. Brown was attending a recent Romney rally, she said she looked around and thought, "No one in that room would vote for her."

Of Mr. Obama: "He's so conciliatory. He's absolutely inspiring. But does he have the skill set to be president?"

On Saturday, she attended a forum hosted by Lifetime and listened to the many female surrogates speak for their candidates. But it was no good.

"I'll be going to Hillary and Obama events today and tomorrow and see them in person," she said. "I'm hoping those will make the difference."