Donald Trump, clever guy that he is, has come up with a new reality show. It’s called “President for a Day” and the way it works is that, every so often, maybe once a month, Trump acts presidential, gives a speech in which an aide is not standing by with meds, and many in the media and politics hug themselves and roll around on the floor, praising the president for his very presidentialness and cheering the emergence of the man who has been there all along but no one in the media or the creepy “deep state” seemed to notice. Thank God, that’s over. He has arrived!

This happened last week after Trump spoke to a joint session of Congress. All over Washington, people fell off their chairs in shock that no one had been insulted, no brazen lies were uttered and no weird conspiracy theories had been advanced. My former Washington Post colleague Ronald Kessler told Newsmax TV that the speech showed “the real Donald Trump.” It was such a relief to learn that whoever it was who had insisted Barack Obama was born in Kenya and who had called Mexicans “rapists” and who had disparaged the heroism of John McCain was not the guy in the Oval Office. Had he been, I know Kessler and others on the right would not have supported him.

At The Wall Street Journal, Peggy Noonan treated the speech like it was a hypodermic: “He normalized himself.” Just like that, roll up your sleeves, Mr. President, this won’t hurt and it will block eruptions of narcissism and self-pity. This allowed Noonan and others to suggest — nay, to hope — that Trump “may have a capacity to grow into the office.” Let us pray.

But within days, the normalization drug had worn off. Trump was having Oval Office tantrums. He was furious that Jeff Sessions had recused himself from investigating the relationship between the Trump administration and the Kremlin. The attorney general would have had a clear conflict of interest, but that is nothing compared to allowing some special prosecutor from within the deep state to get at the truth, which would have been fake news anyway. The ranting and raving was so intense that word of it got to reporters. In many condo communities, this sort of behavior is not allowed.

By Saturday morning, the unreal Trump, the un-normalized one, was back on Twitter. Good morning, America — Barack Obama has had my phone tapped. “This is Nixon/Watergate,” he tweeted. “Bad (or sick) guy!” A still-sleepy America had trouble taking it all in. The New Trump, Mr. Pivot Man, was saying that the then-president of the United States had, during the campaign, tapped his phone. (This is the way those Kenyans are.) Was it possible?

No, said the former president himself. No, said the director of the FBI. No, said the former director of national intelligence. No, said everyone familiar with the procedures for obtaining a wiretap, such as getting permission from a special judge. In other words, no, no, no and no.

But these were some of the same people who denied that 3 million or so illegal immigrants, taking a day off from rampant crime, had somehow cast a ballot for Hillary Clinton, accounting — as anyone can see — for her popular-vote margin. This was the deep state at work again. Ask Steve Bannon. He knows. He was once at Breitbart.

I know what’s happening. I’ve been reading a lot lately about the infatuation some leftists once had with communism. Many felt they lived in an either-or world — either you were a communist or you were a fascist. They could not be the latter so they chose the former. Besides, the reds were the only ones around who fought racism and anti-Semitism.

Somewhat the same thing is happening now. Many conservatives have gone over to Trump because they hate his enemies more than they do him. They see Trump as the un-liberal, the un-PC person, the un-programmed pol who eschews talking points and identity politics. For too many people, their best and only reason for voting for Trump was that he was not Hillary Clinton. They had a point.

But being president for a day is not enough. And sticking with Trump out of a refusal to admit a mistake is hardly wise. One day a month or so, America has a decent president. The rest of the time it’s Romper Room in the White House. Recant, Trump supporters. I won’t forgive you, but history might.

Richard Cohen is a columnist with The Washington Post. His email address is: cohenr@washpost.com.