Bloomberg via Getty Images Republican activists wonder how they can retake control of their party in the aftermath of Donald Trump's nomination. Trump has won over a plurality of GOP primary voters with an agenda that has little in common with the party's longtime goals.

WASHINGTON ― Next week, the party of “four score and seven years ago” and “Mr. Gorbechev, tear down this wall” is set to become the party of I’m building a wall and the judge is Mexican.

Real estate developer-turned-reality TV star Donald Trump, barring an unlikely revolt by convention delegates in the coming days, will officially become the Republican nominee for president of the United States.

The party founded to abolish slavery, and which five decades ago became the home of modern conservatism, will be led for at least the next four months, and possibly the next eight years, by a bullying entertainer with a checkered business record, little apparent knowledge or interest in governing, a long history of insults toward women and marginalized ethnic groups, and a professed admiration for dictators.

“The Republican Party is supposed to be the party of conservative principles. What’s happening right now is a meltdown of the Republican Party,” said New Jersey’s Steve Lonegan, who supported Texas Sen. Ted Cruz’s bid for the nomination and is now running a super PAC to help party activists trying to strip Trump of the nomination at the Republican National Convention in Cleveland.

“We’re going to be looking at this for years, trying to understand this,” he added. “It will be analyzed in the books for a decade or two or three.”

Republicans like Lonegan, of course, have a more immediate question: What now?

How does a party that sent Abraham Lincoln, Theodore Roosevelt, Dwight Eisenhower and Ronald Reagan to the Oval Office retake control from a man who has compared his fears of venereal diseases with fighting in a war and who accused the last Republican president of intentionally lying to the country to win support for an invasion ― but who went on to win the nomination anyway?

“I cannot in good conscience support someone that I know will be a disaster for our nation and our party,” said Beau Correll, a Virginia convention delegate who is suing that state to invalidate a law requiring him to vote according to the result of the March 1 primary, which Trump won.

“If we continue with Trump, it’s going to be total annihilation,” he said.

Many Republicans also worry that Trump’s disorganized campaign and high disapproval ratings make a victory all but impossible, but others have an even more fundamental concern.

“There’s even a greater fear,” one Republican National Committee member said. “What if he really gets elected? Now what do we do?”

Other Republicans are less shy about that possibility. It would be a catastrophe, they say, and it cannot be allowed to happen.

“Whatever Hillary Clinton’s faults, she’s not ignorant or hateful or a nut,” wrote Mark Salter, who was a senior strategist to Arizona Sen. John McCain’s 2008 presidential campaign. “She acts like an adult, and understands the responsibilities of an American president.”

In such a partisan time, and with as polarizing an opponent as Clinton, relatively few Republicans are likely to openly back the other side. Preventing Trump from remaking the party in his own image, however, is a much more readily accepted goal across the GOP’s spectrum.

“This is a pivotal moment in history,” said Kendal Unruh, the Colorado leader of the “Free the Delegates” movement to encourage fellow delegates to modify the convention rules in the coming week to dump Trump.

Yet reaching a consensus on what should replace Trump’s agenda could prove more difficult than imagined ― for the same reasons that Trump was able to win the nomination in the first place. Trump’s victories in the primaries revealed an enormous gulf between what GOP leaders believe their voters want and what those voters actually want.

All of Trump’s rivals for the nomination hit the usual themes that appeal to the Republican “three-legged stool.” They warned social conservatives about threats to religious freedom, guaranteed economic conservatives big tax cuts and rallied foreign-policy conservatives with promises of a more aggressive use of the military.

Meanwhile, Trump smashed the stool until it shattered, focusing his campaign largely on building a wall along the United States’ border with Mexico, raising tariffs, and bombing and torturing terrorists and their families.

The message resonated with the rarely acknowledged fourth leg of that allegorical stool: a segment of the white population, disproportionately Southern and disproportionately undereducated, that has little interest in lower capital gains taxes or fewer business regulations.

Rather, Trump’s racially tinged promise to “make America great again” harkens back to a time when a high school diploma, and sometimes not even that, was all that was necessary to make a middle-class living in a country that was overwhelmingly white.

“What they want to do is go back to 1956. And it’s just not going to happen,” said Mac Stipanovich, a longtime Republican consultant who served as former Florida Gov. Jeb Bush’s campaign manager in 1994. “If that’s who we are, then we’re headed for the ash heap of history.”

Unfortunately for Republicans like Stipanovich, those white, working-class, resentful-of-how-America-has-changed voters appear to make up between 25 and 35 percent of the Republican base. They are the thousands of supporters who fill gyms and arenas around the country to take in Trump rallies. They are the reason the South, despite its high proportion of religious conservatives, supported a thrice-married New Yorker with a shaky theological background who has said he has never sought God’s forgiveness.

Should the “Dump Trump” activists succeed in the days ahead, the party faces the real possibility that the millions of GOP voters who support Trump will stay home in November, almost certainly guaranteeing a Democratic Senate and possibly even a Democratic House.

“If they try to yank it from him, it would be utterly catastrophic for them,” said Norm Ornstein, a scholar at the conservative-leaning American Enterprise Institute. “You would have at least 1,000 delegates on the floor who were strong supporters of his go ballistic. There would be blood on the floor. It would be a bigger disaster for them than swallowing hard and running with Trump on the ticket.”

That Trump will lose this fall seems a foregone conclusion to the anti-Trump Republicans. The only question is by how much, and whether the size of that defeat will affect how quickly and effectively the party can rebuild for coming elections.

Stipanovich believes it would be best for Trump to lose big ― to be “clubbed like a baby seal,” as he likes to put it.

“There’s been this mythology that the reason we haven’t won big races is because we haven’t been crazy enough,” he said, adding that a crushing loss should teach a valuable lesson. “I hope this puts that to rest. ... It’ll be good for the party in the long-term. To get this idea that ‘we have to be crazy in order to win’ out of our system.”

Lonegan is not sure about that theory. A blow-out Trump loss would endanger Republican control of both chambers of Congress, in his view. The only path to take back the White House is replacing Trump at the convention with an actual conservative candidate who has a fighting chance of beating Clinton, Lonegan said, adding that such a candidate would, win or lose, certainly help retain the Senate and House.

In any event, an aggressive “Dump Trump” movement will at the very least start the post-election reconstruction process.

“It’s a necessary battle because we can lay the groundwork for rebuilding,” Lonegan said. “I think the country benefits when you have a liberal Democratic Party and a conservative Republican Party.”

The two views reflect the stark split between the party’s establishment and cultural wings. It was the establishment group ― including allies of Jeb Bush and his brother, former President George W. Bush ― that wrote the “autopsy” of Mitt Romney’s 2012 loss. That 2013 “Growth and Opportunity Project” report urged an immigration overhaul that provided legal status to some 11 million undocumented immigrants. In the view of the authors, a more inclusive party that drew in Latinos and members of other racial groups was the only long-term solution.

But that, according to Lonegan and others in the Cruz wing, was exactly the wrong approach. The Senate’s failed “Gang of Eight” legislation helped alienate the voting base, as did the inability of a Republican-led House and Senate to repeal President Barack Obama’s health care law or cut spending or follow through on any of the other promises they made in the 2010 and 2014 midterms to block Obama’s agenda.

GOP voters could be forgiven for seeing little difference between the parties, Lonegan said.

“To the average voter, it all looks the same in Washington,” he said.

On the far side of that intraparty chasm, the establishment wing blames that all-or-nothing, no-compromise tone for setting unreasonable expectations in the first place, and Cruz is seen as Exhibit A for how not to move the party forward ― sort of a Trump figure with a somewhat more civil tongue.

This rift should sound familiar to those following the GOP in recent years. It’s been cleaving the party since the George H.W. Bush presidency 25 years ago, and has become an open civil war since the second George W. Bush term a decade ago. In that period, Republicans have lost the popular vote in five of the last six presidential elections. Stipanovich wondered when the message that the party needs to grow its base, not retreat into it, will sink in.

“I don’t know how many more times that we need to go to the polls before we convince them of that,” he said.

To Ornstein ― who over the years has come to believe that a dysfunctional Republican Party is largely to blame for official Washington’s failure to solve the nation’s biggest problems ― the party factions’ inability to agree on how to deal with Trump foreshadows the difficulty they will face regrouping after November.

The worst possible outcome for Lincoln’s party: It will have learned nothing from its hostile takeover by a celebrity entertainer with a gift for loudly repeating the things its voting base wants to hear, Ornstein said.

Unfortunately, the way battle lines are being drawn already, and with the all-but-certain-to-continue agitation by talk show hosts and others in the conservative ecosystem, the same factors that allowed a Trump nomination will remain in place after November, Ornstein predicted.

“I just don’t see any resolution to this for a long time,” he said.

Editor’s note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims ― 1.6 billion members of an entire religion ― from entering the U.S.