In a campaign chock full of unbelievable storylines, none was more remarkable than the rise of Herman Cain.

Republican presidential candidate Herman Cain bowed out of the 2012 presidential race on Saturday in Atlanta. (AP Photo/ Richard Shiro)

That Cain — on the strength of his speaking ability and the curb appeal of his “9-9-9” economic plan — spent more than a month as a leading candidate in the race for the Republican nomination provides a telling window into the mood of the GOP electorate on the verge of 2012.

That Cain collapsed in a heap of allegations of sexual impropriety and titanic levels of muddled messaging — all of which culminated in his decision to suspend his campaign Saturday — is proof that an unconventional approach to politics can only get you so far.

“To a base desperate to support change, a fresh face with exciting marketing sizzle but real problems handling policy substance ended up like most new network sitcoms: an interesting concept that gets great ratings early but is cancelled by midseason because the same thing happens over and over with no plot development, even while a dwindling viewership keeps rooting for the show to somehow make it to renewal,” explained Eric Ueland, a prominent Republican strategist.

Steve Schmidt, who managed Arizona Sen. John McCain’s 2008 presidential race, offered a far harsher assessment of the Cain moment.

“That Cain’s candidacy was taken seriously for longer than a nano-second in a time of genuine crisis for the country raises fundamental questions about the health of the political process and the Republican party,” Schmidt said.

At the heart of Cain’s attractiveness to Republican primary voters were two concepts: simplicity and unconventionality.

Cain’s much-discussed — by him — “9-9-9” plan was the essence of simplicity. Scrapping the current tax code, which is universally loathed by Republicans, and replacing it with a 9 percent corporate tax, 9 percent income tax and 9 percent national sales tax has inherent political appeal.

It’s easy. It seems to make sense. And for a party desperately looking for new ideas around which to rally, “9-9-9” seemed to be a perfect fit.

Cain’s “9-9-9” plan also reinforced the other key element of his campaign: his un­or­tho­dox approach to just about everything.

Cain proudly touted the fact that he was the only candidate in the race who had never held elected office before — though he had served in a decidedly D.C. job as head of the National Restaurant Association in the 1990s — and that he would bring the perspective of a businessman and an outsider to the process. He was “bold” he told Republican voters, willing to say and do things that his more cautious (read: political) opponents never would. (How true that wound up being.)

The Republican base, sick of politics-as-usual as practiced by both parties in Washington, loved Cain’s I-am-not-a-politician riff and were, for a time, willing to overlook his occasional flights of rhetorical fancy because, after all, he was touting himself as the unconventional candidate in the field.

“Herman Cain in many ways represented the same qualities that attracted voters to people like [2010 Delaware Senate candidate] Christine O’Donnell,” said Republican senior strategist Terry Nelson. “They thought he would shake things up, and that’s what they want.”

But then Cain blew up (in a good way). And that led to a blow up (in a very bad way).

The simplicity of “9-9-9” turned out to be over-simplification — watch Cain try to explain how his plan wouldn’t raise taxes in an interview on “Meet the Press” with David Gregory — and Cain’s unconventional approach to politics ensured that he had no ability (or willingness) to build a coordinated response against the charges of sexual harassment and an extramarital affair that were leveled at him once he became a top-tier candidate.

So, what does the race look like with Cain gone from it?

In truth, the contest had been moving on — and away — from Cain for the better part of the last month. “Whatever his departure means to the race that’s already happened, it happened a few days ago,” mused one GOP strategist.

The obvious beneficiary from Cain’s slow-motion collapse is former House Speaker Newt Gingrich who rose rapidly as his fellow Georgian’s support cratered.

“Cain’s exit allows Newt the opportunity to coalesce the anti- [Mitt] Romney, conservative base in Iowa and South Carolina, endangering Romney’s path to the nomination,” theorized one adviser to another candidate in the Republican race. (We made a similar case earlier this week.)

It’s worth noting that the idea of Cain’s departure as a major windfall for Gingrich, while widespread, is not entirely born out by the numbers. A Pew poll conducted before Thanksgiving, for example, showed that Cain supporters split evenly between Romney and Gingrich when asked for their second choice.

“[Cain’s] absence mostly means Romney’s chances at top two out of Iowa are enhanced,” said one unaligned Republican operative. “And that matters due to perception of momentum coming into New Hampshire.”

There will also be a scramble among the remaining candidates to harvest the staff and activist talent that Cain had gathered. While Cain’s campaign was, largely, filled with little-known operatives, he did have some well-regarded backers — most notably Kathleen Shanahan, a former senior political aide to then Florida Gov. Jeb Bush.

But, Cain’s lasting legacy in the contest is almost certain to be his “9-9-9” plan — if not the specifics of it, the sentiment of simplicity behind it.

“Like or hate ‘9-9-9’, all the candidates now have seen the real and positive reaction you can elicit with a simple, clear, bold proposal that’s easy to understand and repeat,” explained Ueland.

Texas Gov. Rick Perry’s decision to come out in favor of a flat tax was undoubtedly influenced by the success of Cain’s “9-9-9” plan. Ditto Romney’s focus on his support for cutting spending, capping federal spending and a balanced budget amendment.

Viewed at the highest possible altitude, what Cain’s candidacy proved was the power — and limits — of simplicity and unconventionality in the Republican contest.

“When he started, Herman Cain never had any thought that he could win,” explained one adviser to another candidate in the Republican presidential field who was granted anonymity to speak candidly. “ He figured he might be able to sell some books and double his speaking fees. Then something great and awful happened, the dog caught the car. And of course, dogs don’t know how to drive cars. So he had no idea what to do with it.”