When the results for the 2012 Iowa caucuses are announced this evening, they will seem as foreordained as Julius Caesar’s ill-fated trip to the Forum on the Ides of March. But here is one statistic worth remembering amid the cornucopia of clichés coming your way tonight: In 2008, despite the media’s craving for premature certainty, 17 percent of Iowa Republicans picked their candidate on the day of the caucuses, according to entrance polls.

As a result, it’s a safe bet (and perhaps the only safe bet) that more than a quarter of all GOP caucus-goers are right this very minute still wrestling with some aspect of their participation in this glorious bit of Iowa hokum. That’s why, at the moment, it’s still easy to imagine Mitt Romney (professionalism), Ron Paul (passion) or Rick Santorum (persistence) ending up as caucus king. In fact, even Newt Gingrich has a glimmer of a chance of bouncing back if his cry-me-a-river tears about his dead mother somehow upended voter perceptions.

But whoever is touched by the “Big Mo” tonight—even if the victory margin is just a percentage point—will be portrayed as vindicating a specific theory about how to run for president. After all, what stands out in this campaign cycle is the way each of the six candidates competing in Iowa has pursued a vastly different victory strategy—and politicos, as the ultimate copycat professionals, will be sure to grasp onto the new paradigm (or the one that helped a candidate dramatically exceed his or her poll-propelled projections) as the new model for how you run for president in the 21st century.

Here’s a sneak peak at some of the enduring strategic lessons that campaign tacticians will turn into Iron Laws of Politics based on differing Iowa outcomes tonight:

Mitt Romney Wins. This is the scenario that would make the professional political class feel that all is right with the world. For Romney is the candidate who cleaves to all the verities of modern politics and executes his game plan with the bloodless efficiency of…well, a business consultant. Watching Romney campaign, you can imagine the PowerPoint presentation that created the GOP frontrunner:

  • Stay on message. (Check).
  • Don’t waste too much time on personal campaigning. (Check).
  • Out fund-raise the opposition. (Check).
  • Stiff the press, aside from occasional strategically motivated bouts of accessibility. (Check).
  • Demonize your opponents with negative spots paid for by your SuperPAC. (Check).

A Romney romp in Iowa guarantees that these principles will be etched on stone tablets—and the era of insurgent dreamers will be decreed to be over.

Ron Paul Wins. Talk about casting a pall over the future of the Iowa caucuses. Nothing would do more to discredit Iowa’s exalted status as the opening-gun campaign event than a libertarian landslide or even a one-vote victory. Sure, Iowa has a long isolationist tradition, but still it would be weird for the hawkish Republican Party to give an early boost to a protest candidate with a foreign policy so dovish that it makes Dennis Kucinich seem like Dick Cheney.

Still, a Paul victory would also vindicate the traditional verities about the Iowa caucus. The 40-year justification for beginning the campaign season with a caucus instead of primary is that it is important to measure the hot-house passions of party activists—and not just depend on the more tepid sentiments of mainstream voters. Intensity and organization are the twin pillars of the Paul campaign. And if the first-in-the-nation status of the Iowa caucus survives the fallout from a Paul victory, orthodox candidates on the Romney model will feel increasingly justified in skipping the state entirely.  

Rick Santorum Wins. Under this scenario, the candidate with the sweater vest would have single-handedly brought back 1970s politics. As much out of necessity as strategic vision, Santorum followed the original Jimmy Carter victory model. Such a triumph or even a close second-place finish – outcomes unfathomable just 10 days ago—would underscore that Iowa remains a personal-contact state where you cannot phone-bank it in or depend on a disembodied blizzard of TV ads.  

In the future, elevated national poll numbers would not free any candidate from the tedious necessity of visiting all 99 Iowa counties. And then going back again. Even super-star candidates would cut short town meetings at their own peril, since nothing is as important as answering another run-on conspiracy-theory-driven question from an Iowa voter. In fact, every candidate trailing in the pre-caucus polls and ignored by the press corps would in the future invoke the Santorum precedent. Instead of waving tattered copies of the 1948 Chicago Tribune proclaiming, “DEWEY BEATS TRUMAN,” underdog candidates would hold aloft the front-page of Wednesday’s Des Moines Register ballyhooing the Santorum sweep.  

Newt Gingrich Resurrected (Yet Again). Even if he is not the globe-girdling historical figure of his own fantasies, the former House speaker may be enough of a unique case to defy glib conclusions if he finishes in the top tier in Iowa. It would take more than a Gingrich re-ascension in Iowa to convince political insiders that, as a general rule, candidates can survive an unanswered barrage of attack ads.

Any Gingrich rebound from his fourth-place finish in the final Des Moines Register poll could well  be attributed to the advanced age—ahem, chronological maturity—of Iowa caucus-goers. In 2008, nearly three-quarters of Iowa Republicans who attended the caucuses were more than 45 years old. What that means is that they were old enough to remember the heady 1994 days for conservatives when Gingrich won back the House. A candidate with that kind of historical pedigree just may miraculously survive the downward pull of political gravity.

Gingrich’s survival would, of course, also point to the enduring potency of debates in an increasingly nationalized campaign. But even if Gingrich sweeps Iowa, it is doubtful whether any future candidate would emulate Newt’s summer sabbatical on a Greek cruise or beg Tiffany’s to grant a six-digit jewelry credit line.

Rick Perry Survives. As Alec MacGillis reported from Iowa, the three-term Texas governor even now is stumbling and bumbling his way through a 10-minute stump speech. If Perry somehow manages to escape Iowa with his reputation intact, it would be a signal that personal campaigning has become an over-rated skill, beloved by political reporters but increasingly irrelevant to actual voters. Over-matched in debates, Perry has only one major weapon in his campaign arsenal—looking rugged and sounding compelling in 30-second commercials. If, against the odds, that somehow works for Perry, then America might as well move to a national primary in which voters only see the candidates on their TV screens.   

Michele Bachmann Survives. At this point, Bachmann’s only role in Iowa is to save the institution that vaulted her onto the cover of Newsweek. If Bachmann, bedeviled by meager crowds and dwindling poll numbers, finishes at the bottom of the caucus six-pack, it will sound the death knell for the ludicrously over-hyped Iowa Straw Poll that she won back in August. Getting rid of the Straw Poll—which, incidentally, destroyed the otherwise plausible candidacy of Tim Pawlenty—would be a selfless act of public service by Bachmann, though probably not a gesture that she intended.

In fact, the dramatic rise and fall of Bachmann serves as a reminder that all presidential campaigns follow their own rules and rhythms. And that is why the only caucus-night advice from this corner is skepticism when the TV pundits offer grand over-arching theories based on the voting behavior of little more than 100,000 Iowa Republicans.

Walter Shapiro is a special correspondent for The New Republic. He also writes the “Character Sketch” column for Yahoo! News. Follow him on twitter @waltershapiroPD.