The Republican Party’s politically lethal embrace of Donald Trump is very nearly complete.In endorsing Trump this month, Paul Ryan, the speaker of the House, stipulated that while he and Trump have their differences, “we have more common ground than disagreement.”A President Trump, he argued, will help turn the agenda of the Republican House of Representatives into laws.In a recent interview, Mitch McConnell, the Republican Senate majority leader, said that whether or not Trump believes in limited government, “he’s not going to change the Republican Party,” adding that “he’s not going to change the basic philosophy of the party.”They are expressing the hope of Republicans who have been wary of Trump: that somehow, deep down, he embraces the principles of the pre-Trump Republican Party. Or that even if he doesn’t, he can be cajoled or pressured into adopting them.Either way, the damage that Trump threatens to do to the Republican Party can be contained. The argument is that even if you don’t particularly like or trust Trump, he will not redefine the Republican Party.But he already has. Donald Trump, the Republican Party’s presumptive nominee, is waging an open attack on the party’s core views. Modern conservatism has three elements: a commitment to limited government and economic liberty that enables prosperity; moral traditionalism that conserves our capacity for liberty by producing responsible citizens; and a belief that America, confidently and carefully engaged in international affairs, can be a force for good in the world.Trump rejects all three. He has shown no real desire to limit the size, cost or reach of the federal government. He has no interest in economic liberty as it has been understood since Adam Smith. He wants an economy in which trade and immigration are tightly restricted and the government makes mercantilist deals on behalf of large domestic producers.Trump is the embodiment of the culture of narcissism and decadence that moral traditionalism exists to counteract. Republicans used to argue that character mattered.But apparently that applied only to Democrats like Bill Clinton. Today, we’re told such considerations are quaint. We’re electing a president rather than a pope, after all, so there’s no problem wrapping Republican arms around a moral wreck. At least he’s our moral wreck.The hypocrisy isn’t lost on anyone.And Trump wants America to retreat from world affairs. He believes the United States is too weak to shape events. He wants Americans to think about global affairs in terms of financial transactions that net America money rather than relationships that promote security, freedom and order.Why, then, are Republican leaders unifying behind a man whose views they find offensive? For Ryan, it is an effort to use his influence to pull Trump in a more conservative direction. For others, it is simple party loyalty. For still others, it is fear of opposing a winner, the most powerful figure in the Republican Party. And of course many believe he would be a better president than Hillary Clinton.But the reality is that Republican lawmakers are in this position because Trump was more popular among Republicans than anyone else in the race. We need to acknowledge that his European-style ethnic nationalism, which relies on stoking grievances, resentments and fear of the other, has a powerful sway in the Republican Party today. This is not the conservatism of William F. Buckley Jr. or Ronald Reagan or Jack Kemp; it is blood-and-soil conservatism primarily aimed at alienated white voters who believe they have lost the country they once knew.Trump knows his audience, which explains why, beginning the morning of the Indiana primary on May 3 (the day he became the de facto nominee), he has — among other in-the-gutter moments — implied that Sen. Ted Cruz’s father was implicated in the assassination of President John F. Kennedy; engaged in a racially tinged attack on Gonzalo Curiel, a district court judge presiding over a fraud lawsuit against Trump University; and expressed doubt that a Muslim judge could remain neutral in the case. This is conspiratorial craziness and rank racism — and all of it has happened after we were told Trump would raise his game.The surprise is that so many Republicans are now expressing consternation at what Trump is doing. Has any recent presidential candidate ever advertised quite as openly as Trump the kind of vicious attacks he’d engage in? We were warned in neon lights what was coming. The idea that he will now engage in a “course correction” – that he will flip a switch and transform himself into a decent and dignified man – is laughable.Trump has repeatedly stated that he won’t change his approach. (“You win the pennant and now you’re in the World Series — you gonna change?”) In this one area, Republicans should take him at his word.When a narcissist like Trump is victorious, as he was in the Republican primary, and when he has done it on his terms, he’s not going to listen to outside counsel from people who think they can change the patterns of a lifetime. Republicans have not changed Trump for the better; he has changed them for the worse.So here we are, with Republicans who lined up behind Trump now afraid of being led off a high cliff. If the prospect of a November shellacking isn’t enough to unnerve these Republicans, there’s also this to factor in: What we are talking about is potential generational damage to the Republican Party.Consider this historical comparison: In 1956, the Republican nominee, Dwight D. Eisenhower, won nearly 40 percent of the black vote. In 1960, Richard Nixon won nearly a third. Yet in 1964, in large part because of his opposition to the Civil Rights Act, Barry Goldwater (who was no racist) won only 6 percent. More than a half-century later, that figure has remained low. Trump – through his attacks against Hispanics that began the day he announced his candidacy – is doing with Hispanics today what Goldwater did with black voters in the early 1960s.The less resistance there is to Trump now, the more political damage there will be later.The stain of Trump will last long after his campaign. His insults, cruelty and bigotry will sear themselves into the memory of Americans for a long time to come, especially those who are the targets of his invective.Trump is what he is – a malicious, malignant figure on the American political landscape. But Republican primary voters, in selecting him to represent their party, and Republican leaders now rallying to his side, have made his moral offenses their own.There will be a fearsome price for Republicans to pay for their embrace of Trump.Especially after the attacks on Curiel, Ryan and McConnell, decent men who have criticized Trump harshly, should rescind their endorsement of him – as McConnell just hinted that he might. Trump’s bigotry should earn him their enmity, not their loyalty.