WASHINGTON — Donald Trump’s Republican primary triumph means that this cannot be a normal election. Americans who see our country as a model of tolerance, inclusion, rationality and liberty must come together across party lines to defeat him decisively.

Many forces will be at work in the coming weeks to normalize Trump — and, yes, the media will play a big role in this. On both the right and the left, there will be strong temptations to go along.

Refusing to fall into line behind Trump will ask more of conservatives. Beating Trump means electing Hillary Clinton, the last thing most conservatives want to do. It would likely lead to a liberal majority on the Supreme Court and the ratification of the achievements of President Obama’s administration, including the Affordable Care Act. Conservative opposition could deepen a popular revulsion against Trump that in turn could help Democrats take over the Senate and gain House seats.

But the risks of declaring Trump a morally acceptable leader for our country are higher still, and shrewd Trump opponents on the right are already trying to disentangle the presidential race from contests lower down on the ballot.

Three streams of Republicans are likely to oppose Trump: those to his right on trade and government spending; neoconservatives who oppose his “America First” non-interventionist foreign policy; and the remaining moderates and others in the party alarmed over his outbursts on, among other things, torture, immigration, race, women, Latinos, Muslims, Vladimir Putin, and lest we forget, Obama’s birthplace, Ted Cruz’s father and John McCain’s military service. These honorable and brave conservatives should not lose their nerve under pressure from conventional politicians or the very lobbyists and big donors Trump likes to denounce.

The fact that Trump draws opposition from the most ideological parts of the Republican Party heightens the temptation on the left to cheer his apparent victory. As someone who has argued that the right has long been on the wrong path, I understand this urge.

It’s certainly true that his feat vindicates much of what progressives have said about the conservative movement. Republican leaders have a lot to answer for, and not only the incompetence and timidity of their stop-Trump efforts.

They have spent years stoking the resentment and anger on the right end of their party that fueled Trump’s movement. They ignored the material interests of their struggling white working-class base and also popular exhaustion with foreign commitments fed by interventionist misadventures. Along with many Democrats, they underestimated the anger over trade agreements that accelerated the economic dislocation of the less well-off.

After this election, the GOP will need an extended period of self-examination. But no one on the left should applaud the rise of Trump as representing a friendly form of “populism” — let alone view him as the leader of a mass movement of the working class. He is no such thing. He is channeling the European far right, mixing intolerance, resentment and nationalism.

There will be much commentary on Trump’s political brilliance. But this should not blind us to the degree that Trumpism is very much a minority movement in our country. He has won some 10.6 million votes, but this amounts to less than a quarter of the votes cast in the primaries this year. It’s fewer than Clinton’s 12.4 million votes and not many more than the 9.3 million Bernie Sanders has received.

But never again will I underestimate Trump, having done this a month ago, rashly predicting he would lose the Republican nomination. I clearly had an excess of confidence that Ted Cruz could rally anti-Trump voters and thought a series of wildly outrageous Trump statements would do more harm to his candidacy than they did.

I was dead wrong as a pundit, allowing myself to get carried away by my confidence that, at the end of it all, Americans would see through Trump. I still devoutly believe they will do so, once the campaign moves out of the Republican primaries, but now know how urgent it is to resist capitulation to every attempt to move Trump into the political mainstream.

My friend, the writer Leon Wieseltier, suggested a slogan that embodies the appropriate response to Trump’s ascent: “Preserve the Shock.”

“The only proper response to his success is shame, anger and resistance,” Wieseltier said. “We must not accustom ourselves to this. … Trump is not a ‘new normal.’ No amount of economic injustice, no grievance, justifies the resort to his ugliness.”

Staying shocked for six months is hard. It is also absolutely necessary.

E.J. Dionne Jr. is a columnist for The Washington Post. His email address is: ejdionne@washpost.com. Twitter: @EJDionne.