White House chief strategist Steve Bannon has alternately been described as Donald Trump’s brain, and perhaps more ominously, his “Rasputin.”

Personally, I’d like to think of Bannon as Donald Trump’s rumpled version of George Costanza.

It was George, brilliantly portrayed by Jason Alexander, who famously looked across a table in Monk’s Cafe to offer this wisdom to his pal, Jerry Seinfeld.

“Just remember Jerry,” George said, “it’s not a lie if you believe it.”

Steve Bannon did not write that memorable line. But he was smart enough to be an early backer of “Seinfeld,” the sitcom that turned into a gold mine.

While I have no proof, I also have very little doubt that Bannon has probably recycled the essence of that classic line many times over the past year to remind Trump that lying with total conviction is just as good, if not better, than telling the truth.

Honestly, is there a single line that more perfectly describes Trump’s MO than the one George gave to Jerry as he was about to take a lie detector test?

Let’s see: We’ve got The Donald’s whopper about the thousands of illegal voters riding buses up to New Hampshire to vote for Hillary Clinton. Even Granite State Republicans said he was talking ragtime.

A couple of days ago, we had another tall tale about lines stretching for six blocks, hoping to get into the CPAC convention to hear the president. Every outlet covering the event showed no such lines.

There was also the big lie the president kept repeating at that gonzo press conference in the East Room about how his Electoral College victory was the greatest since Ronald Reagan.

When it was pointed out that both Bill Clinton and George H.W. Bush had larger Electoral College victories, our president folded like a cheap tent.

“Well, that’s what I was told,” he said.

No, that’s what he believed — just more fake news.

This weekend, we heard one of the saddest and most poignant examples of how our president paints the truth. Just nine days into his presidency, Chief Special Warfare Officer William Ryan Owens, a Navy SEAL, was killed during a botched raid in Yemen.

Trump and his daughter Ivanka went to Dover Air Force base to greet Owens’ body. He recalled how he shared a “beautiful moment” with the SEAL’s family, and press secretary Sean Spicer dutifully echoed that account.

Over the weekend, Bill Owens, the father of the fallen SEAL, told a reporter in Miami that he refused to meet with Trump upon the arrival of his son’s body. And now he is seeking an explanation from Trump, or someone around him, about why his son died in the dubious raid.

Steve Bannon will need to fashion an answer soon.