WASHINGTON -When Bill Clinton strolled into the Starbucks in downtown Des Moines for a morning coffee on Jan. 2, he looked every bit the confident political husband.

He chatted cheerfully with a small group of journalists; the news was mostly good.

A national Gallup poll showed his wife, Hillary Clinton, up 18 points over Barack Obama. There were some troubling signs in Iowa, sure, but nobody really believed some rookie senator could knock Hillary off her game with a few fancy speeches.

Privately, campaign strategists had even mapped a victory scenario that envisioned Ms. Clinton wrapping up the Democratic presidential nomination by the Super Tuesday primaries on Feb. 5. It was supposed to be inevitable.

But in that impromptu coffee klatch with Bill Clinton, there was already evidence of jangled nerves.

"Look at my first result," Mr. Clinton said when asked if he feared the consequences of a defeat for Hillary in the next day's Iowa caucuses. He quickly listed the states he lost -- New Hampshire, Maine, Colorado, South Dakota -- before finally rallying to win his party's nomination in 1992.

"You just got to keep going," he said. "It's a long process."

In retrospect, Mr. Clinton's early effort to downplay conventional expectations for the Democratic race seems like a prescient attempt to wave everyone off the notion Hillary could win in a walk.

Only no one noticed, most of all the campaign's decision-makers.

When political historians assess what went wrong with Hillary Clinton's presidential campaign -- now teetering towards defeat -- they will point to a combination of overconfidence, ill-conceived strategy and a flawed message.

"I think Clinton operated under the assumption that she would win all or most of the early contests and would steamroll easily to the nomination," said Peverill Squire, a political scientist at the University of Missouri.

"Clinton's biggest strategic mistake was to assume that the race would be decided by the Feb. 5 contests. That left them unprepared for a longer campaign, both logistically and financially."

The seeds for Ms. Clinton's defeat were sown in the frozen cornfields of Iowa. The former first lady spent more than US$15-million campaigning in the Hawkeye State, even though it was historically unfriendly to her husband and had never elected a woman to statewide office.

She infamously ignored a March, 2007, memo from her deputy campaign manager, Mike Henry, that urged her to abandon Iowa and focus on other states holding early votes in the compressed 2008 primary calendar. Mr. Henry's memo was not only ignored but denounced by Ms. Clinton, and he eventually quit the campaign.

While Ms. Clinton emptied her campaign piggy bank in Iowa, Mr. Obama was quietly organizing for Super Tuesday on Feb. 5, focusing on victory in smaller "caucus" states like Kansas, North Dakota, Idaho and Colorado.

Ms. Clinton's decision to largely bypass those states -- which individually have few delegates and typically vote Republican in general elections -- was her "biggest tactical error," Mr. Squire said. "In this tight contest, every delegate became precious and Clinton conceded too many of them to the much better organized Obama campaign," he said.

"They overspent in Iowa. They didn't have a lot of spare cash after that. It really limited them once they realized they'd goofed," said Larry Sabato, director of the Center for Politics at the University of Virginia.

"Intellectually they knew it would be a tough fight. But they were deceived by their own polls and press clippings."

In retrospect, Ms. Clinton's victory in the Jan. 8 New Hampshire primary -- hailed at the time as a momentum-changing comeback -- turned out to be as much a curse as a blessing.

Rather than being interpreted as a possible fluke, it reinforced the Clinton campaign's confidence and delayed a campaign overhaul that seemed inevitable after Iowa.

Ms. Clinton said she found her "voice" during a campaign stop at a Portsmouth diner, where she welled up while discussing the strains of campaigning and her passion for public service.

It was the most authentic, heartfelt moment of her campaign. But within days the lesson from New Hampshire -- that voters were eager to see less of Hillary the wonk and more of Hillary the person -- had been forgotten.

Ms. Clinton continued to make "experience" the central message of her campaign, even though Mr. Obama's call for "change" had proven the more durable and inspiring among voters. "I think the 'experience' appeal worked with the people towards whom it was directed. Older Democrats who regularly participate [in elections] leaned Clinton's way," Mr. Squire said. "Experience, however, mattered less to the new voters that Obama mobilized. I don't think the Clinton people thought Obama would be able to bring the large numbers of new people to the polls that he did."

It wasn't until early March in Ohio, when Ms. Clinton began casting herself as a champion of the working class, that her message began to resonate.

As some Democrats began feeling buyer's remorse over Mr. Obama, Ms. Clinton found her populist stride downing Crown Royal shots and recounting childhood duck-hunting excursions.

It was an improbable political conversion for a candidate schooled at Wellesley College and Yale University. Still, blue-collar voters warmed to Ms. Clinton partly because of the underdog grit she had shown in battling back from her earlier losses.

But the timing was all wrong. Though Ms. Clinton began winning big in Ohio and Pennsylvania, Mr. Obama's lead was so substantial the former first lady had almost no room for further defeat.

Despite Mr. Obama's own campaign woes, his core constituency of African-Americans and affluent, college-educated white voters proved just as resilient as Ms. Clinton's base of women, seniors and lower-middle class Democrats.

"It was too late. [The blue-collar strategy] worked with the people it was targeting, but the pool of voters in many of the Democratic races was much larger and more diverse than the Clinton campaign anticipated," Mr. Squire said. "In a two-way race, being the working-class hero was insufficient in a number of states."

There were other blunders and missteps, of course. Ms. Clinton relied too heavily on traditional Democratic donors to fund her campaign, while Mr. Obama tapped into a bottomless, 1.5 million-person pool of small donors. Bill Clinton's finger-wagging rants about race recalled his mercurial temper in the White House, and helped send undecided black voters to Mr. Obama en masse. Ms. Clinton's story about coming under Bosnian sniper fire reinforced long-standing questions about her honesty.

In Indiana, exit polls found only 45% of voters believed Ms. Clinton to be trustworthy.

"Hillary Clinton and her campaign underestimated the desire, even among Democrats, to turn the page on the Clinton years," Mr. Sabato said. "It's not that they dislike the Clintons. It's just that they didn't want to go back…. They didn't want to bring back all those old problems."