WASHINGTON -- The unexpected often happens in presidential races, and this election cycle could be no different, except it may be happening in both parties.

Former Arkansas Gov. Mike Huckabee was previously known as a chubby Republican politician who lost a lot of weight and then hit the talk-show circuit to talk about the importance of a healthy lifestyle. Now he is known as the once dark-horse candidate who is suddenly leading in Iowa and running a close second to GOP front-runner Rudy Giuliani in the national polls.

It is a strange twist of politics that has propelled him to where he is right now. The former Baptist preacher draws much -- if not most -- of his support from religious conservatives in Iowa and elsewhere. But he is scorned by other sectors of his party for a dreadful record on spending and taxes, his praise for President Bush's proposed immigration reforms, which included a path to citizenship for illegal aliens, for advocating an end to the trade embargo with Castro's Cuba and for pushing a national sales tax.

If this were not enough to end his chances of getting the GOP's nod, there is his role in the release of a convicted rapist who went on to murder a Missouri woman.

Whether Huckabee can go the distance seems doubtful. He has no national campaign organization to speak of, he is badly underfunded and he is near the back of the pack in New Hampshire.

The story on the Democratic side is in many ways far more interesting. Sen. Hillary Clinton, the national front-runner, continues to slip in the presidential-preference polls in the early nominating contests in Iowa, New Hampshire and South Carolina.

Her chief rival for the nomination, Sen. Barack Obama, has seen his numbers rise in all these states -- and in the national polls, too.

In the meantime, there are reports of discord in Clinton's campaign organization and growing concern that her husband, Bill Clinton, may be doing more harm than good. Insiders say he is unhappy with her chief advisers and has tried to oust Clinton campaign manager Patti Solis Doyle, who has never run a national campaign before.

Doyle has been dispatched to spend the bulk of her time in Iowa, where Obama has overtaken Clinton in the polls.

The tumbling numbers tell the tale. Clinton was clinging to a 6-point lead over Obama in New Hampshire last week. In Iowa, he edged ahead of her by a few points, but among voters most likely to attend the caucuses, he led her by 35 percent to 29 percent, according to a Newsweek poll.

In South Carolina, Obama has surged into a narrow lead, largely as a result of the state's large bloc of black voters.

"What you are seeing is a combination of some of Hillary's soft support shifting and a larger proportion of undecideds going for Obama rather than Clinton," said Bud Jackson, a Washington, D.C.-based Democratic media adviser who is not working for any of the presidential candidates.

"It comes down to electability for a lot of these people. As more undecideds become familiar with Obama and agree with him on the policy issues, they believe he is capable of winning and are more comfortable in supporting him," Jackson told me.

Notably, there is a growing belief inside the Clinton campaign that the media establishment has begun to turn against her. A typical example of this shift was starkly evident this week in a column by Al Hunt, executive editor at Bloomberg News: "The concerns about Clinton ... are that she is devious, calculating and, fairly or not, a divisive figure in American politics. Her once commanding advantage over Obama in Iowa and New Hampshire -- the two critical initial contests -- is evaporating."

This dramatic shift in the way the national press is portraying the New York senator and her campaign forced Mark Penn, her chief strategist, to rush a memo out to her supporters -- acknowledging the race is closer than before but arguing that Clinton is still on course for the nomination.

"No question that this is a fully engaged race, and the polls in Iowa are competitive and tight," Penn said. "But the polls in the other states show meaningful leads as we head into the homestretch, and Hillary maintains a national base in Feb.-5 states that is strong and unmatched."

Still, the decline in her support levels suggests that something deeper is going on among the Democratic base. This week's Gallup Poll showed her dropping from 51 percent in October to 44 percent in November to 40 percent now, while Obama jumped from 21 percent to 30 percent over the same period.

At this rate, with a long 54 days to go before the mega-state primaries on Feb. 5, it is easy to see how the unexpected could happen.