Jan. 22 (Bloomberg) -- New York Senator Hillary Clinton's presidential quest is a study in larger-than-life extremes.

She is the most formidable and most controversial candidate in the Democratic field. Opponents depict her as a left-wing ideologue and at the same time a calculating candidate moving to the political right. Her husband, former President Bill Clinton, may be her biggest asset or a liability. And no one knows if her biggest challenge will be winning her party's nomination or the general election.

Clinton, 59, announced her candidacy on her Web site on Jan. 20, telling Americans that she knew how to beat Republicans and was ``in to win.'' She enters the race as the first female candidate for the presidency with a serious chance to win, and the only former first lady to run.

``Clinton's strengths are her name recognition, her money, her New York base and her effort to define a centrist position,'' said David Schultz, a professor who teaches election-law courses at the University of Minnesota. ``Her weaknesses are the same. She has high name recognition but high negatives, and she needs to turn that around to be successful.''

Arizona Senator John McCain, one of her leading Republican rivals for the presidency, yesterday called Clinton a ``formidable candidate.'' McCain, speaking on NBC's ``Meet the Press,'' said she shouldn't be underestimated: ``I think one of the mistakes we made in 1992 was underestimating her husband's potential.''

Obama, Edwards

Clinton enters a race for the Democratic Party's nomination that already has two other top-tier candidates in Senator Barack Obama of Illinois, who announced last week that he's exploring a White House bid, and former North Carolina Senator John Edwards, who has been campaigning around the country since the last election. Obama has shot up in the polls during recent months as a fresh alternative to Clinton.

In national polls -- wholesale politics -- Clinton leads the Democratic pack. A Jan. 16-19 Washington Post/ABC News found Clinton led Obama 41 percent to 17 percent. Edwards was backed by 11 percent of Democrats and Democratic-leaning independents, according to the poll.

The first caucuses are in Iowa next January, and it's on the retail level of politics -- Iowa, the early primary states of New Hampshire and South Carolina plus the Nevada caucuses --where winning over constituencies such as antiwar and black voters is crucial.

Personal Campaigning

It's in those states, which can stall any presidential campaign and where personal campaigning is a must, where Clinton has work to do. Edwards and Obama have both spent more time in Iowa and New Hampshire than she has.

A December KCCI-TV poll of 400 likely Democratic voters in the Iowa caucuses found Obama tied for first place with Edwards at 22 percent support, compared with 12 percent for former Iowa Governor Tom Vilsack and 10 percent for Clinton.

In New Hampshire, Clinton and Obama are almost dead even, according to a Concord Monitor poll taken in December. Obama drew the support of 21 percent of voters, compared with 22 percent for Clinton. Edwards, 53, ranked third, with 16 percent support, the Associated Press reported.

Clinton's supporters say she is popular among a large segment of Democrats and has experience serving at Bill Clinton's side in the White House. She's survived the scrutiny of two national presidential campaigns, eight years in the White House and six years in the Senate.

`Presidential Wringer'

``She's been through the presidential wringer before,'' said Karlyn Bowman, a public opinion analyst at the American Enterprise Institute in Washington.

She's also a lightning rod for criticism after taking an activist role as first lady and living through the so-called Whitewater investigation of her involvement in Arkansas real- estate transactions. Conservatives paint her as a ``big- government liberal'' largely because of a universal health-care plan she proposed in the early 1990s; the antiwar movement is furious that she hasn't done more to oppose the conflict in Iraq.

There are few people who don't have an opinion of her. The good news for Clinton is that the Washington Post/ABC News poll found that a majority, 54 percent, view her favorably. At the same time, 44 percent say they have an unfavorable opinion, higher than any of her closest competitors from either party.

Bill Clinton's Role

As Clinton seeks the nomination, her husband may prove to be a tremendous asset. Democrats and Republicans alike credit Bill Clinton, 60, with terrific political instincts, and his popularity has only increased since he left office in 2001.

Bill Clinton has always drawn favorable ratings from black Americans, whose support in the South Carolina primary may be critical as Senator Clinton takes on Obama, 45, the most formidable black candidate yet to run for president.

Still, Bill Clinton's strengths as a campaigner might overshadow his wife's. ``She doesn't have the charisma and likeability of her husband,'' said Charles Black, a Republican strategist. And there's always an undercurrent of questions facing the state of the Clintons' marriage.

Senator Clinton will also have to win over antiwar voters in places such as New Hampshire, where opposition to the Iraq war helped Democrats take both of the state's congressional seats in November.

Iraq Vote

To win over those voters, Clinton must overcome her 2002 vote to give President George W. Bush the authority to invade Iraq. While she has routinely criticized Bush's handling of the war, Edwards renounced his vote and Obama wasn't yet in the Senate. Obama has been against the war from the start. Last week, Clinton, after traveling to Iraq, made the rounds of talk shows to voice her opposition to Bush's plan to add as many as 21,500 troops in Iraq.

Stephen Hess, a presidential scholar at Washington's Brookings Institution, said Clinton's statements last week left him ``with the impression that her remarks were written by a committee, measuring exactly how far she should move left, right, up, down.''

``She will pay a price for being so anxious to avoid being controversial,'' Hess said.

Still, she has shown she can appeal to a broad spectrum of voters. During her first Senate campaign in 2000, Clinton won over skeptics in upstate New York, a conservative area that might serve as a model for Republican-leaning states in a national campaign.

Big-Money Race

Clinton has already shown she can compete in the big-money race. She brought in more than $50 million for her Senate re- election campaign last year, even though she lacked any serious competition. By contrast, Edwards, 53, raised just less than $34 million for his failed presidential run in 2004.

Clinton immediately won the endorsement of Emily's List, a powerful political committee dedicated to electing Democratic women who support abortion rights. Her status as the first female front-runner for a party nomination may win her voters who want to be part of a historic ``first,'' Bowman said. Of course, there may also be ``closet'' voters who come out against a woman, she said.

To contact the reporter on this story: Kristin Jensen in Washington at kjensen@bloomberg.net

Last Updated: January 22, 2007 00:12 EST