Donald Trump is in the midst of political death by a thousand cuts.

Already today, two of the Republican Party’s top Senate candidates, Kelly Ayotte and Joe Heck, have reversed course and said they won’t vote for Trump. It will get much worse for him in the coming hours — and with good reason. Mormon lawmakers, including Sens. Mike Lee and Mike Crapo and Rep. Jason Chaffetz, are condemning a candidate whom they can’t possibly defend to their constituents.

John Thune of South Dakota, the third-ranking Republican in the Senate, just called on Trump to resign from his spot as the party’s nominee.

For months, Trump has forced Republicans to choose between party and orthodoxy, party and decency, and even party and country. For many Republican strategists and operatives, it was too much to ask that they remain loyal to the party over their allegiance to higher principles. They stood up to an existential threat to orthodoxy, decency, country — and, accordingly, the party’s long-term interests.

But, among elected officials, party mostly won out. Even Sen. Ted Cruz, who endured Trump accusing him of infidelity, mocking his wife, and suggesting his father was involved in the assassination of President Kennedy, finally came around to being a good soldier for the GOP.

Now, though, with the release of a recording of Trump bragging about forcing himself on women and chasing other men’s wives, Trump is asking Republican officials to pick him over their own political careers. He can’t possibly win that battle.

The tipping point is here.

It’s a familiar moment for those who have spent time on Capitol Hill and watched political careers end over sex-related scandals: Those of Reps. Mark Foley, Chris Lee, Eric Massa and Anthony Weiner among them. When they become toxic for members of their own party, the shivs come out.

This is different. It’s bigger, more consequential. The presidency of the United States, the viability of the Republican Party and the individual careers of countless elected officials are on the line.

Republicans who stick with Trump should be advised that they will end up not only on the wrong side of history, but forever damaged by their choice. Like Democrats who voted to authorize the invasion of Iraq in 2002, Republicans who back him will have to answer for their sins.

By the end of the weekend, it may be too late for Republicans fleeing Trump to claim much credit. They will be the latecomers to the rapidly filling lifeboats in the shadow of the sinking SS Donald.

Curiously, some lawmakers have condemned Trump and even suggested he step aside without withdrawing their support. They can’t possibly expect that Trump will right the ship — especially after he responded to the report of him boasting about assaulting women by attacking a woman (rival Hillary Clinton). He seems to believe that women are to blame when men are accused of committing sexual assault.

Nor can Republicans expect that Democrats aren’t about to dump increasingly devastating oppo on Trump’s head. There’s a whole month left before the election. The video recording and the release of tax records showing Trump claimed a $1 billion loss to the IRS one year are just the first few scoops of dirt at a long, slow and complete political burial.

It would be shocking if many Republican voters didn’t head for the exits now. Clinton’s odds of victory in states with significant Mormon populations — Nevada, Arizona and maybe even Utah — shot up in an instant. Evangelical Christian voters can’t be far behind.

And Trump’s celebration of sexual assault — a subtle undermining of his self-ascribed Casanova status — is just one of a litany of reasons he’s not fit to be president.

He said in his sorry-not-sorry “apology” that he would prefer to talk about policy. That’s an even worse sphere for him. His calls to round up and deport undocumented workers, ban Muslims from entering the country (whether by religious test or a country-of-origin system) and block Syrian refugees would cause harm to entire classes of people. They are fundamentally at odds with American values deeply held by people on both sides of the partisan political divide.

His encouragement of violence at rallies and polling locations, stoking of white nationalism, and derogation of women turn back the clock to the ugliest times in our history.

Indeed, Trump isn’t just unfit for the presidency. He’s unfit for the nomination of a major party and for any public platform whatsoever. There are some things that are more important than party loyalty. Republican officials know that, and they are starting to act accordingly.

Those who move fast may save themselves a lot of pain before the election and for years to come.

Those who are slow to the mark or who go down fighting as Trump’s foot soldiers will come to regret their decisions.

This is a time for choosing in the GOP, and Trump’s the wrong choice for the presidency, the party and politicians who care about their own careers.

Roll Call columnist Jonathan Allen is co-author of the New York Times-bestselling Clinton biography “HRC” and has covered Congress, the White House and elections over the past 15 years.