Here's what's remarkable about the Republican presidential race: With days to go before the voting actually begins, it is quite possible for any of four candidates — and even a fifth — to win the nomination.

This is unprecedented in modern American politics. It reflects the hugely unsettled nature of the campaign, a characteristic historically more the case for the Democrats at this point in the election cycle.

Of course, the five candidates — Mitt Romney, Rudy Giuliani, Fred Thompson, Mike Huckabee and John McCain — do not have equal chances to win. Thompson, especially, is the long shot.

But the fact that there is a plausible scenario for each makes this campaign unique, and therefore uncharted.

The short-term goal for each of them is to make it through the early round of primaries and caucuses so that on Feb. 5 — which has been crowned "Super Duper Tuesday," when 22 states pick Republican delegates — they are one of two or three candidates still standing.

Here is what needs to happen for each of the five to get to that point:

Former Massachusetts Gov. Romney, most of all, needs to win the Jan. 3 Iowa caucuses. Anything but a win there is a huge impediment to his nomination, given his strategy of building on the early contests to provide momentum to the later, big-delegate states and the nomination.

But if Romney doesn't win Iowa, where he has spent a disproportionate share of his time and money, then his lead in New Hampshire on Jan. 8 becomes vulnerable, and his game plan becomes questionable. If he does, however, he'll have to be stopped or else.

Former Arkansas Gov. Huckabee is the hot candidate, having passed Romney in Iowa polls and with his numbers rising nationally.

An Iowa win will earn him a pass through New Hampshire, where the former Baptist minister is not expected to be competitive, and into South Carolina (Jan. 22) and Florida (Jan. 29), where his regional roots are a plus.

Huckabee's rising poll numbers have increased his donations, but he has a smaller war chest than most of the other contenders. And if he doesn't take Iowa, it's hard to see where he goes then for a win.

Former New York Mayor Giuliani's lead in the national polls has shrunk. For him to win the nomination, he'll have to defy history. Giuliani has written off Iowa and is reportedly scaling down his New Hampshire operation with an eye toward conserving resources for later states, such as Michigan and Florida.

If Giuliani does win the nomination without a strong showing in Iowa or New Hampshire, that would be precedent-setting, but he does have the greatest name recognition and the deepest pockets (not counting Romney's personal pockets).

Sen. McCain was given up for dead last spring and summer after he lost his front-runner status, much of his campaign apparatus and most of his bank account. But the improved situation in Iraq, after President Bush adopted the approach he suggested, has showcased his record as a Vietnam War hero as well as his national security credentials.

Former Sen. Thompson faces the most difficult road. He needs to finish third in Iowa — his current spot in the polls — then somehow survive a poor showing that he anticipates in New Hampshire and come back and win South Carolina, defeating Huckabee to become the Southern candidate.

As such, that would then give him the ability to take his case to Florida and then the Super Duper primaries on Feb. 5. For Thompson's strategy to succeed, it would be useful if Huckabee does not win Iowa.

Iowa, New Hampshire, Michigan and South Carolina will winnow the field to two or three contenders by the time Feb. 5 rolls around.

If there are three candidates standing at that point, then some kind of reasonably equitable split of the delegates picked that day could lead to a lengthy campaign and possibly even a brokered convention.

If there are only two major contenders after the pre-Feb. 5 primaries, then it is much more likely that those contests will settle the nomination and avoid the kind of convention that TV executives and political reporters dream about.

Peter A. Brown is the assistant director of the Quinnipiac University Polling Institute; his e-mail address is peter.brown@quinnipiac.edu. He wrote this article for www.Politico.com.

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