Michael Goodwin

ONCE a Putz, always a Putz.

Mayor de Blasio’s announcement that he’s running for president was perfect in one regard: It accurately — and inadvertently — captured who he is.

A lazy faker, a race and class warrior and a problem for those he claims to help.

He came prepared for his big day with two messages. One, he’s for “working people,” a phrase he used repeatedly because he’s trying to convince voters of something that’s not true.

As New Yorkers know, de Blasio’s tax-and-spend, spend, spend regime has contributed to the stratospheric cost of living here, which penalizes the poor and drives the middle class to the exits.

Despite bloated budgets and growing government payrolls, there is an obvious decline in the quality of life. Filth and chaos are everywhere.

The soaring homeless population is one sign, and the near collapse of the Housing Authority is another.

De Blasio’s second talking point was an absolute howler: He can beat President Trump because “I’ve beaten him before and I will do it again.”

Perhaps he was referring to his clownish press conference at Trump Tower, where he threatened to fine the president’s highrises for carbon emissions — in 2030. The mayor picked the site to piggyback on Trump’s name and ended up making a fool of himself.

There is near-universal agreement that the idea of the Putz running for president is a joke. Yet the message he is peddling is no laughing matter and, given how far left Democrats have moved, de Blasio’s nonsense is practically mainstream nowadays.

In that sense, New York is a lab experiment for his “gospel” of redistribution. National Dems

should take heed of the destructive results.

Earlier this year, de Blasio summed up his politics with a salute to socialism: “Here’s the truth, brothers and sisters, there’s plenty of money in the world. Plenty of money in this city. It’s just in the wrong hands!”

For once, he was being honest, because de Blasio sees wealth, success and even public order as enemies of the people. He has held that view for most of his life, with he and his wife sneaking into Cuba for their honeymoon, followed by his work for the Nicaraguan Sandinistas.

That the Castros and Sandinistas were anti-American was not incidental to their attraction.

De Blasio hid his radicalism for years as he toiled away in the City Council and as public advocate. He was a go-along, get-along nobody until he pulled off a stunning upset in the 2013 mayoral primary.

He did it by doing a left-end run around better-known candidates, becoming the harshest critic of the NYPD and Mayor Michael Bloomberg. He courted Al Sharpton and made a TV ad famous for the large Afro of his mixed-race son, Dante, efforts that got him nearly half of the crucial black vote. He won the general election in a landslide.

Thus, in a matter of months, de Blasio ripped off the center-left mask he wore for a decade to become the far-left “progressive” we see now.

That background might have national appeal if his mayoralty were a success. But despite vows to attack income inequality, he is a disaster for those who depend on public services.

His school policies offer a prime example. Unable to move the needle on the racial-achievement gap, de Blasio wants to impose quotas on top schools.

The plan is hitting strong opposition from Asian Americans, who could lose 50 percent of their seats in high schools where admission is based on a single test. That success comes despite the fact that many Asian students are among the poorest in the city and grow up in immigrant households where English is not spoken.

But instead of trying to duplicate that miraculous achievement among black and Latino students, de Blasio wants to abolish the entry test. His message to black and Latino kids is that you can’t succeed on the merits, so we have to dumb down the standards for you.

That is the most debilitating message a public official could send to young people. But selling racial grievance, not helping children, is de Blasio’s business model.

Conspiring with unions, he even wars against charter schools that prove race and class are no barrier to academic success. The mayor also makes it nearly impossible for schools to suspend unruly and violent students.

In schools and elsewhere, de Blasio never lets facts get in the way of ideology. He has decriminalized more and more crimes and wants to close Rikers Island to redistribute criminals to low-security “green” facilities in residential areas. He aims to add 90 homeless shelters to spread around that pain, too.

By now, national Dems should know that New Yorkers who twice elected de Blasio are showing signs of remorse. A recent poll found just 21 percent of city Dems want him to run for president, while 73 percent do not.

Their logic is unassailable: They don’t want the Putz to be president because they know him.