On Tuesday evening, Iowans will brave cold temperatures and strong winds to gather at their local precincts, listen to the last political speeches they will have to hear in the state for months, and then decide which Republican to support in the 2012 presidential race. Soon, the rest of the nation will stop bothering Iowa, and start stalking New Hampshire in the week leading up to the Granite State's Jan. 10 primary. The media, the consultants, the volunteers, and especially the candidates will flee the Hawkeye State… and every single one of them will claim some sort of victory or vindication with the results, whatever they may be.

The run-up to the caucuses has been a most curious spectacle, not just this year, but every four years for the last few decades, and not just because the caucus is actually non-binding. That's right: There are no presidential convention delegates assigned from Tuesday's results. Instead, the attendees will cast votes in a non-binding presidential preference ballot while choosing county delegates to a March convention, which will choose delegates to the state Republican convention in the spring. Delegates to the national convention get chosen at that time, separately from the caucuses. Mike Huckabee won the caucus four years ago, but John McCain secured all 28 Iowa delegates months before the 2008 convention.  

The true strangeness of the caucuses is about the immense importance placed on Iowa voters. It's mostly a myth that Iowans bring some sort of unique qualities to the presidential vetting process. Candidates spend their time in Iowa simply because it's first.  If New Hampshire's primary came first — and that is a binding primary, one that produces actual delegate assignments — then candidates would spend months toiling in the Granite State to develop grassroots support networks and media narratives of growing strength. If the similarly non-binding caucuses of Nevada or Minnesota occurred first, candidates would have spent the last several months extolling the virtues of Vegas or the luxury of lutefisk, rather than the ethereal goodness of corn-based ethanol.  

It's mostly a myth that Iowans bring some sort of unique qualities to the presidential vetting process.

That doesn't mean that the last several months have been wasted, or that Tuesday's caucuses are meaningless. It's the process that matters, not the venue, and Tuesday night is the final test of the campaigns and the candidates. While every candidate in the race will craft a media narrative to explain how his or her position in the caucus demonstrates excellence and reach, most people will realize that a poor finish doesn't bode well for the future of any campaign. The only exception to this might be Jon Huntsman, who has mostly ignored Iowa to focus on New Hampshire. Given Huntsman's latest numbers from New Hampshire, though, a pass Tuesday from the media and punditry is merely a postponement of the inevitable.  

Who will win in Iowa? Let's start with the near dead heat for win, place, and show in this horse race. Take Mitt Romney. Given the polling over the last week and the organization that his campaign has quietly built, Romney is likely to either win this or finish very close to the top. After being shocked by Mike Huckabee in 2008, Romney has managed expectations this cycle by limiting his time in Iowa. But all along, he's known that a strong Iowa finish leading into a big win next week in New Hampshire would only cement the impression that his nomination is inevitable. Don't be surprised to see Romney come in first.

Ron Paul's grassroots support is legendary, but it's also outside the mainstream in a couple of important ways. It tends to skew more to the college students who may be out of Iowa on winter break, and to independents and Democrats who may or may not reliably show up to the caucuses. Paul's past has also caught up with him, as the media has recently taken a serious look at the controversial content of his newsletters from the 1990s and the foreign policy positions that put Paul outside of the mainstream of the GOP. Polling from the Des Moines Register, considered the gold standard for surveying Iowa caucusgoers, showed a significant drop in Paul's support late last week. He could drop to third, but probably no further, and that will be good enough to keep Paul's organization in high spirits.

Two weeks ago, Rick Santorum languished near the bottom of the polls. One week ago, Iowans began to align themselves with the candidate who has spent the most time in their state, tirelessly visiting every county and seemingly greeting every voter. Over the weekend, every pollster put Santorum into second or third place — but within the margin of error of the lead. An outright win by Santorum would be a long shot, but no longer an impossibility. A finish in the top three probably raises his chances in socially-conservative South Carolina, but don't expect Santorum to spend any time in New Hampshire outside of the debates this weekend, as he'll need to conserve his resources. Santorum could end up becoming a rallying point for social conservatives if the other candidates begin to withdraw.  

What about the others? Newt Gingrich and Rick Perry have dropped into wild-card status in Iowa, moving in opposite directions. Support for Gingrich has declined to the point where the former speaker has now gone quite negative against Romney. But Romney's not the candidate who has taken Newt's support; that mostly went to Santorum, and the rest to Perry, who has rebounded a little since his collapse in the fall. Perry has never been shy about going after his opponents, and was one of the first to go negative on Santorum after his polling surge began in Iowa. Either Gingrich or Perry could make a surprise showing and finish in the top three, but Perry's funding and organization make him a more likely spoiler. Both will almost certainly keep pushing after Iowa, but don't be surprised to see Gingrich follow Perry's lead and skip New Hampshire for a last-ditch effort in South Carolina.

Michele Bachmann needs a win the most, and is least likely to get it. She bet it all on her native state, but Iowans abandoned her months ago. Her latest ad argues that Bachmann will be the Margaret Thatcher of the U.S., but Thatcher became prime minister by ascending to leadership within her party. Bachmann started this campaign on the outside looking in, and that is almost certainly how she will finish it. Bachmann insists that she will continue her campaign regardless of how she finishes in Iowa, but it's going to be difficult to attract donors after finishing dead last in one's birth state.

After Tuesday, the circus moves to New Hampshire, where Romney leads by almost 30 points over his closest challengers. If Romney wins Iowa and in next Tuesday's primary, the test that follows in South Carolina might end up turning into a coronation instead.