The GOP's real pickle: If/when Trump bows out

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For Republicans eager to cast The Donald out of the GOP presidential primary, a warning: The only thing more difficult than a Trump in the race, may be a Trump who's no longer in the race.

The apoplexy over how much damage Trump is doing to the party brand—and its eventual non-Trump nominee—in his present role as a recalcitrant, incendiary, front-running candidate, may well be trumped (if you will) by the fulminations and machinations of an ex-candidate.

It would be one thing if Trump went graciously and serenely into surrogacy, whenever that moment came, giving a no-strings-attached endorsement to the eventual party nominee. But given everything we've seen so far—including his threats of running as a third-party candidate—that scenario seems highly improbable. More likely, Trump's nonaggression pact, let alone his endorsement, will require some careful calculations and significant Kabuki.

Donald Trump
Daniel Acker | Bloomberg | Getty Images

With that in mind, CNBC.com reached out this week to several top alumni of Mitt Romney's 2012 campaign, which successfully walked the Trumpian tightrope last presidential election. Are there any lessons for today? Yes, and no.

Even in those kinder, gentler days of 2012—when Trump's demagoguery was limited to birtherism, and his political clout mostly self-proclaimed—his entreaty was treated with a great deal of consideration and strategy.

For Romney's first meeting with Trump at his eponymous tower in midtown Manhattan, the campaign intentionally stationed the governor's advance man, Will Ritter, outside the building to serve as a media decoy.

"It goes to show you how conflicted we were about the Trump endorsement," recalled Eric Fehrnstrom, Romney's former senior advisor. "We wanted the benefit but we didn't want any photos to appear."

Ritter declined to comment on the episode, wryly emailing, "Can't a guy just stand on a NYC sidewalk anymore?" Answer: not anymore.

Even after the endorsement had been confirmed, there remained a palpable unease in Romneyworld prior to it being announced during a joint press conference in Las Vegas, just before to the Nevada primaries.

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"We were biting our fingernails," Fehrnstrom said. "I remember saying to [Romney Press Secretary] Andrea Saul—she was with Mitt in Vegas—'Make sure Trump limits his remarks.' She says, 'Guys, you are asking for the impossible.'"

In the end, Good Donald came through.

"It is my honor—real honor—and privilege to endorse Mitt Romney," Trump said from the podium, as Romney looked on, tightly clutching wife Ann's hand, as if the two of them were parents in the audience of their child's first solo recital.

But Trump made things easy that day, saying his piece about the the American place in the global economy and freely relinquishing the mic after a few minutes.

"At end of the day, we made the right calculation," said Fehrnstrom. "He was kind to us in the media. Can you imagine, with Mitt as nominee, if he had to put up with Trump taking shots at him? I think the campaign made the right decision, but it was entirely dependent on circumstances of that race and what was going on then, and here in 2015, it is an entirely different set of calculations, so each campaign has to arrive at their own Trump strategy."

Ahead of the first GOP debate next week in Ohio, How To Handle Trump has become the organizing principal of the entire Republican race. On the one end of the spectrum is Texas Gov. Rick Perry, who had solicited Trump's endorsement in 2012, but who has since asserted himself as Trump's chief critic, railing against the real estate investor as a cancer on conservatism. Then there's Texas Sen. Ted Cruz, a reliable instigator in Congress, who has nevertheless strained to remain in Trump's good graces.

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"I think (Cruz) is probably smart, in that respect," said Fehrnstrom. "I would avoid (Trump) for the same reason professional boxers don't get into the ring with unorthodox fighters."

Trump's latest Republican target is Wisconsin Gov. Scott Walker, who elicited Trump's wrath after one of his top fundraisers referred to Trump as a "DumbDumb" in a recent donor email.

Stuart Stevens, who was Romney's chief campaign strategist, said the Trump playbook must ultimately wait to be written.

"I think you have to wait and see what happens, how Donald will handle himself in the debates," Stevens told CNBC.com. "I thought what Governor Christie said is dead on: He will be as serious a candidate as he chooses to be."

Despite Trump's across-the-board lead in the polls, Stevens still thinks the safe money is on the real estate mogul pulling out before the first primary ballots have been cast.

"The one thing we know about presidential campaigns," he said, "is it doesn't matter how you enter the process, you leave the process humbled. And that is true for everyone who wins and loses, and I don't see that Donald Trump has the temperament to subject himself to the voters in Iowa and be judged."

Kevin Sheridan, who served as Rep. Paul Ryan's communications director on the Romney campaign, wonders if Trump can even be brought into the fold this election.

"If I was counseling a candidate," he said, "I would say that you should think long and hard if you want that embrace, but at the same time acknowledge the electorate's frustration in the political process or whatever that phenomenon that is fueling Trump, because it is not necessarily about Trump."

Just be mindful how you phrase it.

"I think the one leave-behind [from 2012], is that no one has come out of a scrape with Donald Trump looking better than when they went in," said Fehrnstrom.

Read MoreChristie: Trump would hurt presidential credibility

Beyond the candidates, the Republican Party faces perhaps an even more complicated calculus with Trump. In 2012, the Republican National Committee figured out how to acknowledge Trump at the convention without giving him an ever-dangerous prime time speaking slot. Will he settle for anything less than that this time? And if not, what's the chance of him getting such a slot, after months of degrading the party establishment?

"Zero," said Brian Walsh, a GOP consultant and former communications director for the National Republican Senatorial Committee. But Walsh added that the party couldn't afford Trump going third-party rogue, a move he said "would all but assure Hillary being elected."

So what do Republicans do when Donald Trump finally drops out? It's both too early to plan, and yet not early enough. So many things to worry about. So many bad options to weigh. Maybe for now, for the party's sake, at least, it's best that he stays in the race.