The Republican Party could be maimed for years following the 2016 presidential election, party insiders tell the Washington Examiner.

They worry not just that front-runner Donald Trump will lose the general election to Hillary Clinton, but that the disruption he's proudly caused will mean lost elections and diminished influence for years to come.

The outlook is so bad that a contested convention to stop the New York businessman is not their biggest worry, they say, even as he gets close to the 1,237 delegates he needs to secure the nomination. Sure, they don't relish the four-day food fight being prepared for the GOP gathering in July, especially as millions would view it on television and online.

The deeper concern is that Trump will remake the party in his own image, breaking it to pieces and ending its existence as America's recognizable and electable conservative party.

"A Trump victory could transform the GOP into a populist, nativist, statist party, very different from today's GOP," Alex Castellanos, a veteran Republican strategist, said Monday. "If Trump is the nominee, it is likely there will be an independent conservative party."

Trump was set to pad his lead in delegates on Tuesday with expected victories in primaries in five states in the mid-Atlantic and northeast, stirring further speculation about what his nomination would mean for the future of the party. Trump is a unique figure, a billionaire real estate developer who transformed himself into a national celebrity by hosting a popular reality television program.

The New Yorker has a history of publicly zinging rivals and critics with crude insults, a style he brought to the campaign. Trump's unorthodox approach netted him more primary wins and raw votes than his more seasoned competitors — and he is the only candidate who can still capture the nomination before the convention. But Trump's behavior comes with a downside.

His personal favorable ratings are dangerously low — among the worst in modern polling — with the kinds of voters he needs to win in November, including Hispanics, women, young voters, and independents. Meanwhile, about a third of self-identified Republicans consistently vow never to vote for Trump. In the latest national poll, his unfavorable rating among all likely voters was 28 percent; Clinton's stood at 37 percent.

That's why GOP strategists are pessimistic about Trump's ability to close a polling gap with Clinton that sits near 10 percentage points. The Democratic former secretary of state to President Obama might be the most unpopular, untrustworthy candidate running for president this year if not for Trump, who Republicans fear will taint the party far beyond 2016.

"What happens to a party that nominates a person who is negatively viewed by two-thirds of the electorate? There is no historical precedent for this, at least in modern times," said David Winston, a pollster who advises House and Senate Republicans.

Top Republicans welcome the Trump campaign's talk of the front-runner's pending pivot to more presidential conduct, and they are pleased to see his staff professionalize with strategists that have experience advising presidential candidates. Last week, during a quarterly business meeting, Republican National Committee leaders were publicly optimistic about Trump's prospects for unifying the party and beating Clinton.

Privately, GOP officials conceded their concerns.

Beyond questions of electability, Republicans who have toiled in the party worry that Trump would junk a conservative platform that has stood largely intact since Ronald Reagan's party-defining presidency. House Speaker Paul Ryan has led aggressively to preserve the GOP as a conservative party, pushing back against Trump.

The front-runner is promoting an isolationist foreign policy; opposes reforming entitlement programs like Medicare and Social Security; would restrict U.S. trade with other countries; limit legal immigration; and talks about expanding the scope of executive power to strong-arm foes and combat critics.

So, the Republican Party would still exist, the letterhead on the stationery would still look the same, it would still occupy the same Capitol Hill headquarters. But the GOP's conservative base that believes in free markets, smaller government and robust U.S. foreign policy could exodus, leaving behind a populist redoubt.

"We survive a contested convention. I think the bigger question is can we survive a Trump nomination?" said Brad Todd, a Republican consultant who previously ran a super PAC supporting Bobby Jindal's presidential bid.

Trump's two remaining rivals, Sen. Ted Cruz of Texas and Ohio Gov. John Kasich, have their own challenges when it comes to unifying the party, if they manage to hold Trump under 1,237 and beat him in a floor fight for delegates in an open convention at Quicken Loans Arena. Trump leads in delegates with 845, a figure that could hit 1,000 by the time Tuesday's votes are tallied; followed by Cruz with 559 and Kasich with 148.

Cruz and Kasich wouldn't threaten the Republican Party as a vehicle for conservative governance and could leave it in better shape to recover post-2016. But either of them winning the nomination could spark Trump supporters to bolt the party or sit out the general election. In a new poll, 56 percent of voters who supported Trump in a GOP primary said they would follow Trump to a third party run, a move he has refused to rule out.

The danger is stark enough that Reince Priebus, the national Republican chairman, pled for unity during a speech last week to RNC members. That's probably not the sort of plea Priebus envisioned having to make at this critical stage of the election cycle, with Clinton as the GOP opponent, no less. It's indicative of the predicament Republicans find themselves in.

"It is essential to victory in November that we all support our candidate. This goes for everyone, whether you're a county party chairman, an RNC member, or a presidential candidate," Priebus said. "Politics is a team sport and we can't win unless we rally around whoever becomes our nominee."

Despite the risks, some Republicans are less anxious that the worst will come to pass.

In Washington, GOP lobbyists see Trump as a dealmaker who will be satisfied to cut deals and declare victory. Given that they expect the House to remain in GOP hands, K Street figures Trump will shed his populism and work with congressional Republicans on the only agenda that can get their votes, in other words, a conservative agenda.

Some Republicans on Capitol Hill agree, and were no doubt relieved to hear top Trump aide Paul Manafort tell RNC members last week that his candidate's bombast has been a big act to win the primary, and he will soon modulate. Other Republicans aren't convinced that Trump will change, ideologically or otherwise.

But this group of Republicans still believes party unity is possible, if and when Trump is the nominee, because of Clinton. Next to Obama, there might be no Democrat that Republicans would relish beating other than Clinton, a sort of blood feud that goes back to her husband's White House reign, from 1993 to 2001.

That, the Supreme Court and possibly one last chance to repeal the Obamacare health care regime hang in the balance of this election. Conservatives aren't going to abandon the GOP with so much at stake. That's largely why Ken Blackwell, the former Ohio secretary of state and revered conservative figure, is predicting unity despite his belief that the nomination won't be decided until the convention.

"If Donald Trump is the nominee, you will have a Republican Party that will not be the Republican Party that has been substantially influenced by the conservative movement," said Blackwell, who has not endorsed in the primary. "If in fact it is Trump, our work is cut out for us. It will not be as conservative a party but it will be a clear alternative to the Clinton-led Democrat party."