Hillary Clinton is “one of the finest public servants this country has produced” and “a person of extraordinary integrity,” says Mayor de Blasio.

He is completely confident that “measures were taken to comply with the letter and the spirit of the law,” so no biggie that Clinton hid her official e-mail correspondence on her own private servers where they could be protected from scrutiny and/or deleted.

De Blasio may have an undeclared interest at stake: Maybe he’d like to be a cabinet secretary under President Hillary. But his unqualified defense of Hillary’s secretive and likely illegal off-the-books communication system is typical of even those members of his party who have little to gain from covering for her.

Hillary is infallible. Hillary is above reproach. She can’t ever, ever have done anything wrong, ever, and even when she has been shown to have done something ethically revolting, the reason we know it’s no big deal is that it is said to be a big deal by those slimy Republicans.

Associated Press? The New York Times? Obvious GOP front groups.

As Democratic Sen. Ben Cardin put it, “People have different ways of communicating. I have a granddaughter who does nothing but text. You’ll never find a letter written with her. So everybody’s different.”

Right, and Bernie Madoff? He just had a different way of managing a hedge fund.

The Democratic Party, with whose members Hillary has had an approval rating of 88% or higher since 2009, has the attitude of passengers on a storm-tossed ship that only one person can steer. “O Captain, my Captain!”

Except they aren’t aboard the ship. The ship is still in the dock. It doesn’t sail for more than a year. The Party isn’t stuck with Capt. Hillary. It could find another leader.

So, why the fervent loyalty to someone with such a troubled ethics record? A woman whose foundation accepted donations from foreign countries while she was Secretary of State? A woman who is such a poor communicator that her approval rating actually dropped while she was on a book tour last year?

The Democratic Party … has the attitude of passengers on a storm-tossed ship that only one person can steer.

So oblivious of her own record that she is trying to make an issue of the gender pay gap despite having run a Senate office in which women were paid 72 cents on the dollar compared to men?

Democrats behave as if Hillary is the only conceivable presidential candidate with sufficient stature, but any Democratic elected official who became the nominee would naturally rake in donations from the usual left-wing groups, massive media exposure and the national high profile that comes with it.

Democrats say Hillary has been a public figure for so long that she’s already been “vetted,” i.e., no more scandals about her can possibly emerge. Never mind the two major, and brand-new, scandals that have emerged in just the last two weeks. The percentage of voters who view her as honest has plunged 10 points since April, according to Fox News polling.

The real reason Hillary commands such tribal loyalty is that she is, apart from the non-candidate Elizabeth Warren, the only political “celebrity” available, and Democrats are obsessed with star quality. Republicans are currently debating the merits of competent, proven leaders like Scott Walker, John Kasich and Mike Pence, who stand little to no chance of being recognized by the average waitress, much less attracting adoring throngs when they walk down the street.

As recently as 1992, the Democratic nominee could be the little-known governor of a tiny state, but today only celebrities need apply. The party of government can’t very well make the case, as Republicans might, that their leader is simply the more competent manager of bureaucratic institutions. Democrats have to make the very idea of governance romantic, transformational, inspirational, even millennial.

The real reason Hillary commands such tribal loyalty is that she is … the only political ‘celebrity’ available, and Democrats are obsessed with star quality.

They don’t believe in heaven but they feel perpetually on the verge of an ecstatic, all-redeeming breakthrough to a higher plane of consciousness that will arrive if we just pass another fossil-fuel tax or one more equal-pay mandate.

Only an icon of liberalism can light the path to this new and better land.

If there is one ship’s captain Hillary does resemble it’s the skipper of the Apollo, the converted troop transport that puttered around the Mediterranean in the 1970s. At the helm, L. Ron Hubbard demanded total unthinking allegiance, treated his bedazzled Scientology followers more harshly than an admiral treats the lowliest swabby and punished real or perceived infractions without mercy.

But don’t take my word for it: Even David Axelrod has noticed the scary zealotry of the Church of Hillarology.

“There’s this cult of personality growing up [around her], and that’s dangerous,” Axelrod has said. “She’s going to have to correct that when she’s a candidate.”

“Correct that”? When she’s a candidate she is going to positively revel in it.