Donald Trump speaks at a rally in Madison, Ala., on Feb. 28. (Jabin Botsford/The Washington Post)
Michael R. Strain is a resident scholar at the American Enterprise Institute.

In the beginning, it was very entertaining. His descent down the golden escalator. His ability to fill stadiums. Taking children for helicopter rides. Having his private plane tip its wing to the crowd. Telling a kid that he is Batman. Smacking around the other candidates. “I’m really rich.” “We will have so much winning if I get elected that you may get bored with winning.” “I went to the Wharton School of Business. I’m, like, a really smart person.” “This report was not designed for a man of Mr. Trump’s massive wealth. … As of this date, Mr. Trump’s net worth is in excess of TEN BILLION DOLLARS.”

The presidential campaign of Donald J. Trump was funny. Now that he has won New Hampshire, South Carolina and Nevada, it isn’t funny anymore. Now that he has won the endorsement of New Jersey Gov. Chris Christie, any remaining trace of humor is gone. All that remains is terrifying.

Some look for a silver lining in the hope that Trump’s policy rhetoric may be posturing. I agree that, if he’s elected, there’s a good chance he won’t pursue the policies he has championed. He might not round up and deport 11 million men, women and children who are living unlawfully in the United States in less than two years. He might not establish a police state. He might not impose massive tariffs and risk destructive trade wars. He very well might govern as a centrist technocrat. As a guy who can make a deal. Maybe so; maybe not.

But the American president is not merely a package of public policy proposals. The president is our head of state — our chief public representative, a living symbol of the nation. However he would actually govern, Trump is simply unfit to hold this office.

He called for a Muslim registry. He wants to send Syrian refugees back to Syria. He has publicly employed misogyny and has publicly enumerated lists of women with whom he would like to have sex. He has mocked the disabled. He admires Vladimir Putin. He might have ties to organized crime. From the start, his campaign has appealed to the darker angels of our nature, generating support by attacking the vulnerable and rousing fear and suspicion of the other. It is no surprise that years before the 2016 campaign, Trump was a leading figure stirring suspicion that President Obama was not born in the United States.

Trump is deeply morally offensive. Why would we assume he would not continue to be that way as president?

His campaign spokeswoman, Katrina Pierson, tweeted the following in 2012: “Perfect Obama’s dad born in Africa, Mitt Romney’s dad born in Mexico. Any pure breeds left?” National Review wrote about this last month, arguing that Pierson’s “nativism includes a bizarre streak of anti-Catholicism,” among other ugliness. Why does Trump continue to employ her? Why would we assume his White House press secretary would be any different?

And don’t forget this weekend’s atrocious incident in which Trump initially declined to condemn the Ku Klux Klan. That alone makes him wildly unfit to be president of the United States.

Why would we assume that Trump wouldn’t continue to stir fear and suspicion as president? Why would we think he would check the ugliness at the White House door?

On Friday, after his triumphant rally with Christie, he threatened the news media: “I’m gonna open up our libel laws, so when they write purposely negative and horrible, false articles, we can sue them and win lots of money.” Conservatives believe in limits on government power. Why should conservatives assume that a President Trump would respect those limits? Candidate Trump seems not to respect the First Amendment. Would President Trump?

This goes beyond politics as usual. The other remaining viable Republican and Democratic candidates — Ted Cruz, Marco Rubio, Bernie Sanders and Hillary Clinton — represent an unusually varied, but still conventional, menu of politicians. Trump is something else entirely.

He may yet lose the GOP primary race. But whatever happens this election cycle, conservatives need to get serious about the duties required of a self-governing people. Those conservatives who hold positions of power and influence need to honor their duty to address the concerns and needs of the American people by using the power of government and public policy. The conservative entertainment establishment needs to stop whipping up the public with allegations that their leaders have betrayed them by not doing the impossible. They need to use their influence responsibly and constructively, remembering their duty to the people they reach. And voters have a duty to use the power of the ballot box responsibly, as well.

Donald Trump could win not just the GOP nomination, but the White House. He must be stopped. But he can be stopped only by us.

It’s not funny anymore.

Read more:

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What the pope did, and didn’t mean, when he said Trump wasn’t a Christian

Donald Trump’s foreign policy doctrine was wrong 25 years ago. It’s even worse now.