Once again a witness who was supposed to help a hostile Congress make the case against the administration has made a mockery out of the televised congressional hearing.

When is Congress going to realize these events are disastrous for the reputation of the lower chamber and are contributing to America’s loss of faith in its august institutions?

Trump lackey Corey Lewandowski was supposed to sit timidly in front of the House Judiciary Committee and acknowledge shame-facedly that he’d been instructed by the president to obstruct justice.

The dopes on the Judiciary Committee who decided to subpoena him had every reason to know the event would be a disaster. It was.

At best, Lewandowski is a goon. I’ve seen the video showing him grab Michelle Fields, a reporter who asked him a mild question and worked for a website friendly to President Trump. (Lewandowski denies it, and authorities declined to prosecute.) At worst, he’s like the bug-eyed character in the Bill Murray movie “Stripes” who instructs everyone to call him “Psycho” rather than his real name, “Francis.”

Only in this case, when Congress effectively said, “Lighten up, Francis,” the way the drill sergeant did in “Stripes,” Lewandowski went in for the kill.

He put on quite a show. There hasn’t been a show like it since Woody Allen served as his own lawyer and cross-examined himself in the movie “Bananas” after declaring that the proceedings were “a travesty of a mockery of a sham of a mockery of a travesty of two mockeries of a sham.”

Lewandowski sneered at the hostile questioners. He disobeyed directions to read aloud the memo Trump dictated to him with instructions for Attorney General Jeff Sessions — instructions that clearly suggested an effort to obstruct justice but that Lewandowski never delivered.

He chose the moments at which he said he had been instructed by the White House not to answer questions about his conversations with the president.

Rep. Eric Swalwell went back and forth with Lewandowski about reading the memo aloud and whether he was ashamed of having written it. Lewandowski said he had never been ashamed of anything he had ever done and asked Swalwell if maybe he were ashamed.

And in the most comic moment of the day, he called his interlocutor “President Swalwell,” a cutting ironic reference to the congressman’s ludicrous abortive bid for his party’s nomination.

How did this lunacy happen? Well, in some respects, it always happens. Congress has the constitutional obligation to oversee some aspects of executive branch conduct. But the dramaturgy of the high-stakes hearing (one of the ways the House and Senate sometimes conduct oversight) is usually bad news for Congress.

It was bad news for the members when a Republican-dominated Congress tried to use the Benghazi hearing to destroy Hillary Clinton and instead, after 11 hours, made her look good and made themselves look terrible.

It was even worse news in 1987 when Col. Oliver North came before a joint House-Senate committee investigating the Iran-Contra scandal. The idea was that North would bring down the Reagan administration. Instead, he was so charismatic a witness that he turned the entire proceeding on its head. “Oliver North, Star Witness,” said the cover of Newsweek after North’s dazzling turn.

The point here is not to defend these three witnesses — Lewandowski, Clinton or North. In my view, they’re all sociopaths able to keep weirdly calm under intense pressure. But there is something inherently discomfiting about the way these hearings are conducted.

You have a single person, sometimes with a lawyer next to him or her. And that person is facing literally dozens of people, more than half of whom are extremely hostile and whose questions sound like efforts at verbal assassination. Unless the ordinary viewer is deeply and profoundly committed to one side, the effect is to generate automatic sympathy for the lone soul in the chair coming under attack.

In Lewandowski’s case, the only real punishment the committee can inflict would be to find him in contempt of Congress. And one gets the sense that Lewandowski might welcome such a charge, since he clearly wants to position himself as a fighter against Democratic overreach and do some serious national fundraising for a senatorial bid in New Hampshire.

If Congress wants to keep ritually humiliating itself, fine, it should continue to do so. But when, no matter who is in charge, 80% to 90% of Americans say they disapprove of the way Congress does things, members of Congress really have no one but themselves to blame.

jpodhoretz@gmail.com