Republican presidential candidate Donald Trump speaks in Mississippi last week. (Rogelio V. Solis/Associated Press)

In the late 1940s, Sen. Joseph McCarthy arrived in Columbus, Ohio, to make a speech but within an hour allegedly was shooting craps. “It was a disgusting sight,” according to a source, “to see this great public servant down on his hands and knees, reeking of whiskey and shouting, ‘Come on, babies, Papa needs a new pair of shoes.’ ” What Papa really needed was a kick in the butt.

That kick — being censured — was administered in 1954. The Senate had finally had enough of McCarthy. He was a liar and a demagogue, a concocter of evidence and an abuser of witnesses, but what probably mattered most to many of his colleagues is that he was rude to them. Three years after he was censured, McCarthy was dead, leaving a widow, a child and an unsavory term: McCarthyism. Even that, though, is in danger. Trumpism may trump it.

Donald Trump is not quite yet ready to fill McCarthy’s boots. He has the late senator’s gift for exaggeration and self-worship, and he needs the spotlight the way a vampire needs blood. But he holds no public office, least of all a Senate seat. He commands no committee, the way McCarthy did the one that investigated the Army. He cannot subpoena and he cannot compel testimony and he does not have access to FBI and other confidential files that can be used to destroy careers and reputations. All this is something to shoot for.

As with McCarthy, Trump has his reluctant defenders. On TV and elsewhere, they acknowledge that he goes too far. They concede he says ugly things about women — that crack about Carly Fiorina, the swipe he took at Megyn Kelly and, of course, his juvenile remark about Hillary Clinton’s restroom break — but they let that go. They concede also that he probably should not have called Mexican immigrants “rapists” and stated that the Mexican government was sending them north of the border just to get rid of riffraff.

They admit also that Trump’s crack about John McCain not being a hero was really despicable but then, as Trump himself pointed out, he had attended a military prep school so he knew something about war and torture. He was probably required to make his bed first thing in the morning — and that, as you can imagine, is sheer hell.

Presidential candidate Donald Trump released his first television ad spot on Jan. 4. (Donald Trump)

It was the same with Muslims. Here, too, it is conceded that he went too far. His proposal to bar entry to any of the world’s 1.6 billion Muslims is impractical. He would have to include almost all Indonesians, not to mention the occasional Saudi billionaire. So, who is going to stop everyone at the airport and ask them to prove they are not Muslim? (Are you now or have you ever been a Muslim?) I foresee some problems.

But as with McCarthy, Trump’s apologists insist he has put his finger on major problems. With McCarthy, it was particularly the number of alleged communists in the government who were supposedly doing the bidding of the Soviet Union. McCarthy was buttressed in his claims by the occasional real spy who was caught and by the support of FBI Director J. Edgar Hoover, whose files were fodder for right-wing journalists. In fact, there was no domestic communist menace. By the end of World War II, there was no domestic communist party to speak of.

It is similar with Trump. What I hear is robust condemnation of him followed almost instantly by a whispered assertion that he is on to something. Maybe so. Our immigration laws are broken and need to be fixed. There is an Islamist threat, but it comes from sociopathic radicals, not from the vast Muslim community.

McCarthy’s contempt for the truth was evident from his earliest days in public office. Yet countless Republicans thought he could be useful and, besides, he raged against the political correctness of his day. His defenders insisted he said what needed to be said. Never mind the exaggerations and the lies. He supposedly spoke a greater truth.

Trump’s constituency, we are told, is primarily composed of white males who top out at a high-school diploma. But recently I’ve been talking to people who have advanced degrees, some of them female. They all, to a person, condemn him, but then the other shoe drops — the one about you having to give him credit for assailing PC.

We’ve been this way before. But this time, instead of a demagogue on his knees shooting craps, we’ve got one who owned the tables in Atlantic City.

Read more from Richard Cohen’s archive.