Standing on a platform between his gold-trimmed Boeing 757 and a dilapidated airport hangar packed with thousands of supporters—their earsplitting screams echoing off moldy concrete walls, rusted pipes and metal doors shedding a decade-old paint job—Donald Trump deepened his voice to ape the Republican political class that has failed to halt his march to the party’s presidential nomination.  “You know, I get a lot of heat: ‘He’s not conservative,’” Trump said Saturday on a runway near Memphis, Tennessee, mimicking rivals’ complaints about his unorthodox political views compared to past nominees. “Folks, I call myself a common-sense conservative.”  As the sun set behind the New York businessman, long-time backers of the party wondered if their day was done, too.  “Everyone is holding their breath for the next two weeks,” said Stanley Haar, an investment manager and Republican donor who said he won't vote for Trump if he's the party's nominee. “I'll vote third party.”  The next two weeks are lined up to clarify the Republican nominating race like no other similar stretch of the campaign. Heading into these pivotal contests, Trump finds himself on the verge of seizing the nomination with a campaign that has bewildered rivals and party leaders alike, including those who bemoaned Trump’s insolent yet captivating tactics, but largely stayed on the sidelines.  The single biggest day of voting in the Republican primary is Tuesday, when nearly half of the delegates needed to secure the nomination are up for grabs. Trump is favored in most of those contests, and if he repeats with convincing wins like he had in each of the last three primary contests, it would help a clear path to the nomination and deliver him control of a party that has offered dire warnings of what such an outcome would mean. He captured almost 50 percent of the support in a national CNN poll released Monday, 33 points ahead of his nearest competitor, Senator Marco Rubio.  “The Republican Party would be split apart if he became the nominee,” Rubio said about Trump on Friday in Oklahoma City.  Sentiments similar to Rubio's have been expressed by some of the party's top figures. But little has been done to stop Trump, who is threatening to upend many of the party's fundamental tenets with calls to make it easier to sue and standing aside as Russia takes the lead in fighting Islamic State militants in Syria.  The last Republican president, George W. Bush, avoided jumping into the fray until it was too late for his brother Jeb, who suspended his campaign last week. The last three nominees have been similarly absent from battle: Bob Dole praised Trump in order to slight Ted Cruz. John McCain backed the long-shot candidacy of his friend, Lindsey Graham, and then, citing the need to defend his own Senate seat this year, declined to engage the billionaire.  Mitt Romney, the party's nominee in 2012, called on candidates to release their tax returns a month ago, but waited until last week to use it as a cudgel against Trump. Romney waited until Monday to forcefully reject Trump, doing so in a tweet. "A disqualifying & disgusting response by @realDonaldTrump to the KKK. His coddling of repugnant bigotry is not in the character of America," he said.  In the meantime, Trump has gained support from 43 percent of likely Republican voters in Massachusetts, where Romney was a popular governor before seeking the White House.  “I feel so strong, I feel so great,” Trump, talking about his poll numbers, told a crowd of more than 7,000 people in Madison, Alabama, on Sunday.  Demonstrators quietly protest at a campaign rally for Republican presidential candidate Donald Trump on Feb. 28, 2016, in Madison, Alabama.  As Trump has gained popularity after mocking the disabled and prisoners of war, several presidential candidates made feeble attempts at stopping him. Former Texas Governor Rick Perry and Graham both said Trump would spell disaster for the party should he become the nominee, but they had neither the support nor the money to make that argument stick.  “My party has gone batsh-- crazy,” Graham said Thursday in Washington, calling Trump a “nut job.”  In introducing Cruz at a rally on Monday in Dallas, Perry spent much of his speech attacking Trump's past support of an assault-weapons ban and the billionaire's statement that he doesn't need forgiveness from God. He also took issue with the billionaire's explanation for not serving in the Vietnam War, which was winding down as Perry joined the Air Force in 1970s.  "When our country needed Donald Trump back in the '60s, I'm not sure where Donald Trump was," Perry said. "Oh, that's right, he had those bone spurs."  Bush’s team had more money than anyone. But when the pro-Bush super-PAC that paid for the bulk of Bush TV campaign finally attacked, many of those spots were trained on Rubio.  Liz Mair, a former Republican National Committee spokeswoman, was among the first to wage an anti-Trump campaign in November. Her group's pitch to donors was that a Trump nomination would hand Hillary Clinton, the front-runner for the Democratic nomination, the presidency.  But prospective donors told her they wouldn't donate because they were convinced to only give to Right to Rise, the pro-Bush super-PAC. It “was very irritating, and contributed directly to the problem,” she said. “It's clear that someone in Jeb Bush world has got a lot to answer for there.”  Rubio’s supporters complained about the attacks from Bush, but the senator’s presidential campaign aggressively avoided Trump’s attention. Rubio criticized Trump’s call to ban Muslim immigration in the wake of terrorist attack in San Bernardino, but promptly made a similar appeal by suggesting he’d support surveillance on mosques.  In many ways, Rubio has modeled his own campaign on Trump's.  The author of the immigration reform bill that passed the Senate in 2013 with bipartisan support, Rubio now wants to first seal the border. Rubio says his position changed not after Trump found success in calling for a wall along the U.S.-Mexico border, but because of the rise of the Islamic State militant group in the Middle East.  Most recently, Rubio has shed his caution and, like Trump, includes a caustic comedy routine as part of a revamped stump speech. Rubio has shown he can give as good as he gets, cracking up crowds by insulting the front-runner as a con man and a fraud who would be hawking watches in New York City if he hadn’t been born the son of a real estate mogul.  On Sunday in Virginia, Rubio said Trump doesn't sweat “because his pores are so clogged from all that spray tan” and said that Trump had tiny hands.  “You know what they say about guys with small hands,” Rubio told a crowd of about 2,000. “You can't trust them.”  “Rubio should have done this weeks ago,” Patti Smith, a Republican voter in Oklahoma, said after Rubio’s rally in Oklahoma City on Friday. Smith said she’s backing Rubio, but said it might be too late for him. “They’re all intimidated by Trump.”  Rubio’s behavior isn’t completely out of character. In Florida, he’s well known for a quick, biting wit. As state House speaker, he would regularly tease colleagues in front of the full chamber. As the Florida House majority leader, a position that functioned as the party’s attack dog in the legislature, he would fire off biting press releases that left Democrats in a mix of anger and admiration.  Senator Marco Rubio greets attendees as he arrives to speaks during a campaign rally in Salem, Virginia, on Feb. 28, 2016.  “Marco has enough sense to smile while he cuts you,” said Dan Gelber, who was Rubio’s Democratic counterpart in the House. “He does it in such a collegial way that you’ll be laughing. He’s like the Steph Curry of the Republican Party—the baby-faced assassin.”  But Rubio’s team has so aggressively protected the Floridian’s image—quick to argue over the smallest details in news stories, carefully selecting friendly conservative media outlets for access—that outside his home state few Republicans recognize this version.  Now, many don’t believe it.  “He can be strong when he needs to be, but he’s not like that all the time,” said Becky Baker, a Rubio voter in Okmulgee, Oklahoma. “I don’t think it comes as naturally for him as it does for Trump.”  For others, Rubio's caustic persona reeks of inconsistency and further validates their feelings that Trump—who has switched positions on abortion, military funding, and taxes over the years—is the archetype of authenticity.  “He’s trying to do Trump, but it’s making him sink even lower,” Craig Nakutis, a 45-year-old Trump backer in Jackson, Tennessee, said about Rubio, whom he initially supported. “I thought he was going to be better than he was, but it’s a little too late. And Trump is coming into his own.”  For his part, Trump is embracing his role, referring to himself as the messenger of a political movement during a weekend campaign swing through the South.  “There has never been anything like this that has ever happened,” Trump said in Madison.  “I don’t want any money, I don’t need any money, I need you to do one thing on Tuesday,” Trump said. “We’ve got to win by a lot. We knock the hell out of everybody. The movement is going.”  —With assistance from Bill Allison, Terrence Dopp, and Sahil Kapur.
The realization that the billionaire real estate developer is poised to become the Republican presidential nominee is starting to set in for many in the party who oppose him.