Christopher Gannon / MCT / ZUMAPRESS.com Republican presidential candidate Ron Paul speaks during a campaign stop in Waverly, Iowa, Dec. 9, 2011.

Go to any Ron Paul event and the audience is part of the tale. They’re younger, rowdier, more socially diverse than Republican rally regulars. Any one of them might have driven across the state to see Paul speak or be able to riff at length about Austrian economic theory. Any one of them also might be a Democrat or an independent, a fact that’s poised to play a big role in Paul’s story in 2012.

The partisan breakdown of Paul’s current coalition is striking. Byron York writes:

In a hotly-contested Republican race, it appears that only about half of Paul’s supporters are Republicans. In Iowa, according to Rasmussen, just 51 percent of Paul supporters consider themselves Republicans. In New Hampshire, the number is 56 percent, according to Andrew Smith, head of the University of New Hampshire poll. The same New Hampshire survey found that 87 percent of the people who support Romney consider themselves Republicans. For Newt Gingrich, it’s 85 percent.

The fact that roughly half of Paul’s primary supporters are Democrats or independents is probably an asset in selling his general election viability, which his fellow Republicans have frequently called into question. In a recent CNN survey that polled hypothetical head-to-heads between Obama and Paul, Mitt Romney, Rick Perry, Michele Bachmann and Newt Gingrich respectively, Paul tied Romney in performing best against the President in large part because he outperformed all the other GOP candidates among Democrats, independents, 18- to 34-year-olds and non-white voters.

(MORE: The Generational Divide That Will Define 2012)

While an electability argument is a key part of any nomination process, if Paul ends up under-performing high expectations in Iowa next week, this big-tent dynamic could end up being the culprit. Paul has a significant lead in most Iowa polls at the moment, but as Mark Blumenthal explains, polling in Iowa has historically underestimated arch-conservative candidates and overestimated the performance of those with more moderate coalitions:

Polls may have sampled the likely caucus-goer universe too broadly, including too many moderate and independent-leaning Republicans, and thus diluted the greater support for more conservative candidates among the narrower caucus-goer universe…. The few polls that disclose their “rate of incidence” typically show that they sample a portion of the electorate that represents at least two to three times the tiny number of eligible voters who actually participate in the caucuses.

In short: Many of the people being polled won’t actually show up. This could spell double trouble for Paul as youths and non-Republicans are precisely the types who’ve been oversampled in the past. Turning out young people has always been a challenge (although Obama did it to great effect in 2008), and Democrats and independents who want to caucus for Paul will have to switch their registration to Republican before they’re able to take part.

(MORE: Ron Paul’s Army Eyes an Upset in Iowa)

Of course, Paul is himself a conservative candidate–the most conservative by some definitions–and cut from similar cloth as some of Iowa’s past insurgent winners. The most frequently cited hurdle to turnout–the act itself of shuffling into stuffy church basements on a cold winter night–doesn’t seem like it would be a problem for Paul’s dedicated army. And in what looks to be a low-turnout year, the overall effect of his foot soldiers may be amplified.

It all adds up to incredibly unpredictable Iowa contest and an outcome that could be totally novel for Republicans, who are still adrift in post-Bush soul searching. As Rick Santorum observed Monday, there are now three parallel primaries playing out within the GOP: the mainstream moderate race, the conservative true believers contest, and the libertarian primary. The results in Iowa will likely splinter–Romney and Gingrich dividing the first section of the party, Perry, Bachmann and Santorum the second. Paul has the libertarian wing to himself though and the prospect that he could claim a significant number of delegates at the Republican convention in August with such a broad, unusual coalition marks a sea change for the party.