The Democrats are lucky the February debate in New Hampshire took place on a Friday night, when relatively few were watching — because if they wanted to deliver the message to the working-class white people who delivered the upper Midwest and the presidency to Donald Trump in 2016 that they should stick with him rather than voting blue in November, they did a brilliant job of it.

Tom Steyer, the billionaire who’s trying to buy a win Bloomberg-style in the South Carolina Democratic primary, issued a stark warning at the beginning of the Democratic debate Friday night in New Hampshire: Trump has the economic numbers that can help him get reelected, and Democrats are going to need to have a strong message to overwhelm it.

About an hour into the debate, they found their message: America, Bernie Sanders said, is “a racist society from top to bottom.”

One by one, the candidates echoed the message that “systemic racism” characterizes America.

“We can’t legislate away racism,” said Andrew Yang, because racism runs so deep in the American soul.

Joe Biden, verbatim (poor Joe): “The fact is that we in fact there is systemic racism.”

Elizabeth Warren even declared that “we need race-conscious laws in education, in employment, in entrepreneurship to make this country a country for everyone.”

By which she means the law should actually be written to privilege people of color.

It’s a fashionable message, and if there’s one thing the Democrats love to be, it’s fashionable. It’s The New York Times’ “1619 Project” nonsense about how slavery is what founded this country.

And when you live in a liberal media bubble, its allure is hypnotic — especially since it seems to offer a pathway they can follow to appeal to the African American voters who make up 25% of the Democratic primary electorate and who may now be up for grabs since Joe Biden face-planted in Iowa earlier this week.

I’m not saying these people are crazy but — these people are crazy. This is crazy talk, and not only because it’s a rotten, lousy lie and a grotesque distortion of history and simple truth.

It’s crazy talk because, unless I’m very much mistaken, you don’t win the presidency by telling the American people the country they live in and that so many of us love is rotten at its core.

It’s one thing to trash Trump, which they did as they always do. It’s one thing to blame him for all kinds of stuff. It’s another to spend an evening trashing the United States of America as a systematically unjust and even evil place whose rot reaches its very foundations.

You don’t win the presidency by telling a majority of voters — some of whom are the very voters you need to flip to win — that the system is unfairly rigged in their favor.

Even Trump, who began his presidency by talking about “American carnage,” did not say America was bad at its root — rather, he said it had ceased being great, and he was going to make it great again.

I wasn’t happy with the way he talked about this country either, but he didn’t say our problems were systemic and that effectively we were born out of evil.

The only candidate with a positive message, and the desperate energy and enthusiasm that only a last stand can really provide, was Amy Klobuchar. She needs a miracle to get into this race, and if a debate could provide one, she might have gotten it. Biden didn’t.

Mostly, though, what we saw was a party in danger of walking itself off a cliff.

John Podhoretz is editor of ­Commentary magazine.