GOP leaders are scrambling to minimize Donald Trump's dominance in the polls, leaving many wondering what would happen if no one candidate wins a clear majority before the national convention. (Jenny Starrs/The Washington Post)

GOP leaders are scrambling to minimize Donald Trump's dominance in the polls, leaving many wondering what would happen if no one candidate wins a clear majority before the national convention. (Jenny Starrs/The Washington Post)

The presentation is an 11th-hour rebuttal to the fatalism permeating the Republican establishment: Slide by slide, state by state, it calculates how Donald Trump could be denied the presidential nomination.

Marco Rubio wins Florida. John Kasich wins Ohio. Ted Cruz notches victories in the Midwest and Mountain West. And the results in California and other states are jumbled enough to leave Trump three dozen delegates short of the 1,237 required — forcing a contested convention in Cleveland in July.

The slide show, shared with The Washington Post by two operatives advising one of a handful of anti-Trump super PACs, encapsulates the newly emboldened view of many GOP leaders and donors. They see a clearer path to stopping Trump since his two losses and two narrower-than-expected wins in Saturday’s contests.

In private conversations in recent days at a Republican Governors Association retreat here in Park City and at a gathering of conservative policy minds and financiers in Sea Island, Ga., there was an emerging consensus that Trump is vulnerable and that a continued blitz of attacks could puncture the billionaire mogul’s support and leave him limping onto the convention floor.

But the slow-bleed strategy is risky and hinges on Trump losing Florida, Illinois and Ohio on March 15; wins in all three would set him on track to amass the majority of delegates. Even as some party figures see glimmers of hope that Trump can be overtaken, others believe any stop-Trump efforts could prove futile.

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This moment of confusion for the Republican Party is made more uncertain by the absence of a clear alternative to Trump. Cruz, Rubio and Kasich each are collecting delegates and vowing to fight through the spring. Among GOP elites, the only agreed-upon mission is to minimize Trump’s share of the delegates to enable an opponent to mount a credible convention challenge.

“It’s one thing if [Trump] goes to the convention and he’s got 48 percent, 49 percent of the delegates,” Tennessee Gov. Bill Haslam, a Rubio supporter, said in an interview here. “Then it’s a hard thing to see if there’s a convention floor battle. But if he goes to the convention and he’s got 35 or 40 percent, that’s a whole different thing.”

[Inside the Rubio meltdown: Frustration, perceived blunders]

Other governors voiced exasperation not only at the prospect of a Trump nomination but also at the political culture that gave rise to his candidacy.

“We’ve got this Enquirer magazine mentality,” Gov. Gary R. Herbert of Utah said in an interview. “We are subject to this reality-TV voyeurism that is taking place. Fast-food headlines, no substance, all flash. The Twitter atmosphere out there, snarky comments on email, Snapchat. Everything is superficial. . . . We’ve got to wake up, America.”

Similar conversations were under­way in Sea Island, where the American Enterprise Institute think tank held a policy forum.

“Despite the fact that the story right now is panic in the streets, throw the baby out the window and hope the firefighter catches her . . . hope springs eternal,” said Arthur C. Brooks, AEI’s president. “Nothing is inevitable.”

Trump could get a bounce Tuesday with the Michigan and Mississippi primaries: He is expected to win them, although there are signs of the races tightening. But the next Tuesday is seen as the more decisive moment. Winner-take-all Florida is ground zero, and polls show Trump’s lead there slipping.

The stop-Trump movement’s leading super PAC, Our Principles PAC, is adopting what its operatives call a “surround sound” strategy in Florida: more than $3 million in television advertisements, plus direct-mail pieces, digital ads, phone banking and emails — all designed to sow doubts about Trump’s character, convictions and fitness for office.

“There is not a silver bullet,” said Brian Baker, a strategist involved with planning the super PAC’s activities. “It’s the cumulative effect of all of these messages.”

[Remaining hopefuls are not ready to let Cruz be the “Stop-Trump” candidate]

Baker also advises the political work of the billionaire Ricketts family, whose matriarch, Marlene, gave $3 million in seed money to Our Principles PAC. Baker and Michael Meyers, president of TargetPoint Consulting, developed the delegate-count slide show that was shared with The Post.

Our Principles PAC is also eyeing an aggressive push in Ohio, where Kasich is governor, and has prepared a possible television ad casting Trump as an outsourcer because his branded clothing is made in China and Bangladesh, the group’s advisers said.

Katie Packer, the super PAC’s president, said: “His path to 1,237 goes through Florida, Ohio and Illinois. If he can’t win at least two of those places, it’s going to be very, very tough for him to get to 1,237.”

The super PAC is attracting new donors, including Randy Kendrick, wife of the owner of the Arizona Diamondbacks baseball team, who said she was moved to act by Trump’s provocative rhetoric. “Dictators arose because good people did not stand up and say, ‘It’s wrong to scapegoat minorities,’ ” Kendrick said.

Some party establishment figures are assisting the super PAC, including former New Hampshire governor John Sununu, who confirmed that he has been calling friends and urging them to make donations.

[Calls for the GOP to unite against Trump tear the party apart]

A separate group, American ­Future Fund, also is trying to take Trump down with a $2.75 million series of ads in Florida. Some spots feature people who say they were duped by Trump University, while others star veterans speaking out against him or characterize some of Trump’s business associates as shady.

A third group, the Club for Growth, is advertising against Trump in Florida and Illinois and is assessing a possible barrage in Ohio.

David McIntosh, the Club for Growth president, said donors recently were hesitant to fund anti-Trump ads but have come around in the past couple of weeks.

“After South Carolina, I got questions — ‘Can he be stopped? You’re running a fool’s errand,’ ” McIntosh said. “My answer was: ‘It worked [in Iowa], and even more importantly, it has to be done. We can’t just cede this ground.’ ”

Trump reacted Monday with a tough ad in Florida depicting Rubio as a fraud and ticking through the greatest hits in the senator’s opposition-research file. The narrator calls Rubio “another corrupt, all-talk, no-action politician.”

For Cruz and his allies, the intensity of the anti-Trump ad campaign is a welcome relief. It frees them to focus on their main target, at least in Florida: Rubio. The Cruz camp hopes a home-state loss would force him to drop out.

“There is so much anti-Trump messaging out there, it’s flooded,” said Kellyanne Conway, president of Keep the Promise I, a pro-Cruz super PAC. “What could we say that isn’t out there?”

Some Republican donors are not on board with trashing Trump, however.

“There’s a group that thinks, ‘Look, Trump is likely to be in­evitable here, and let’s not tarnish him,’ ” said Fred Malek, the RGA’s finance chairman.

[How the Republican Party created Donald Trump]

Strategist Liz Mair said she has found it difficult to persuade many donors to pony up for Make America Awesome, her anti-Trump super PAC.

“Republican donors are acting like the parents of teenage alcoholics,” Mair said. “They see all the signs of problems, but they don’t really want to admit and address the problem because that would entail them acknowledging that they didn’t do the right things along the way.”

Idaho’s governor, C.L. “Butch” Otter, who met with many donors in Park City over the weekend, said he heard “a lot of concern” about the GOP’s fracturing.

“There’s people that always say, ‘You’ve got to go negative,’ and I really struggle with that,” Otter said in an interview. “To, in a gentlemanly way or a ladylike way, point out the other person’s record is one thing. But to get into some kind of a name-calling deal, I don’t think is very beneficial.”

But Haslam, Tennessee’s governor, reiterated the urgency of slowing Trump before he accumulates too many delegates. Otherwise, party elites risk the appearance of trying to steal the nomination from him at the convention.

“That is probably the most dangerous situation for the Republican Party,” Haslam said. “If he gets there with not a majority but close to a majority of the [delegates] and doesn’t get the nomination, that’ll be very difficult. He could say, ‘I’m going to ask all of my folks to sit this one out to show them how big we are.’ Who knows?”

Matea Gold in Washington contributed to this report.