The impact will be felt the most in the Democratic race, where longtime front-runner Sen. Hillary Rodham Clinton was humbled by a third-place finish and political newcomer Sen. Barack Obama's star power was affirmed.

For the Republicans, the vote was an embrace of former Arkansas Gov. Mike Huckabee but also very much a rejection of a field of candidates that party members find less than appealing. Undeniably, the results were a humiliating loss for former Massachusetts Gov. Mitt Romney, the man who had all the money and all the organization.

Both parties have little time to analyze what happened here, with the crucial New Hampshire primary only five days away. But what Iowans did was remarkable, particularly in their demand for change and an almost palpable sense that they are sick and tired of partisan wrangling and the blue state-red state divide.

In some ways, the night was comparable to John F. Kennedy's famous win in the West Virginia primary in 1960. Just as Kennedy had to prove a Catholic could win in an overwhelmingly Protestant state, Obama needed to show that a black contender could prevail in an overwhelmingly white state.

By winning so convincingly in one of the whitest states – Iowa is 95 percent white – the Illinois senator wasted no time dismissing that question. Not only did Obama win, he helped generate an unprecedented increase in the turnout.

Now the questions swirl around Clinton.

It might not be fair, since the difference between second and third place was so slight. But politics are not always fair. Third place deals a serious blow to Clinton's campaign, stripping it of its aura of inevitability and guaranteeing her a state-by-state battle none of her strategists envisioned just a few months ago.

That aura had obscured the reality that the New York senator and her message were never an easy fit for this state and its caucus system. Her early support for the war in Iraq and cautious refusal to move further leftward hurt her with the activists who make up the core of Democratic caucus-goers.

Now she must be wondering why she didn't take the advice of some advisers to bypass Iowa.

Clinton isn't the first front-runner to stumble in this state with its quirky caucus rules. Ronald Reagan, Michael Dukakis, Walter Mondale, George H.W. Bush, Robert Dole, Howard Dean, Edward M. Kennedy – all entered Iowa leading the pack and all fell short of expectations. Three of them – Bush, Dukakis and Dean – finished third here.

But all except for Dean and Kennedy recovered to win their party's nomination. Clinton's recovery will be difficult, though, for two reasons.

First is the short time between Iowa and next week's New Hampshire primary. It usually takes two days for an “Iowa bounce” to materialize, and it usually does not dissipate for a week. In 1980, Reagan had five weeks to recover from his Iowa loss, and he needed four of those weeks to right his campaign.

“There is almost no time for her to change things,” said veteran Democratic strategist Mary Anne Marsh. “The only event that can change the dynamic is the debate Saturday night. The next five days are going to be some of the most fascinating political fighting ever seen in New Hampshire.”

The second factor working against Clinton is that Obama is not the normal insurgent. When candidates such as Gary Hart in 1984, Richard Gephardt in 1988, Pat Buchanan in 1992 and John McCain in 2000 scored surprisingly well in the early going, they could not sustain their success when the campaign broadened into big states. They had neither the organization nor the money needed.

Obama has both. And his win here will boost something else he has generated – excitement.

As Clinton switches gears, the results in Iowa were also deeply disappointing for John Edwards, who had bet everything on the state where he finished a strong second four years ago. The former North Carolina senator is woefully underfunded compared with Obama and Clinton, and he needed a win here to keep his funds from drying up.

The Republican outcome is likely to have a less consequential impact. It signals weakness in Romney's campaign. And it may hasten an end to the once-promising campaign of former Tennessee Sen. Fred Thompson.

But Huckabee's good showing does not make the former Arkansas governor the national front-runner. The results also helped Arizona Sen. John McCain, who campaigned sparingly here but now has a chance in New Hampshire to beat up Romney near his home turf.

“There is this enormous vacuum in the Republican Party,” said independent analyst Charlie Cook. “And when you have a vacuum, a group like the evangelicals can seize the initiative and that's exactly what happened.”

Romney was never able to make a personal connection with Iowans, showing poorly when contrasted with the folksy and likable Huckabee. And Romney never countered the criticism on his record.

“The flip-flop label stuck to Romney and really hurt him,” said Sherry Bebitch Jeffe, a University of Southern California political analyst who traveled to Iowa to observe the caucuses.