Having won re-election, Mayor de Blasio is resuming his so-far-disastrous bid for national progressive leadership, starting with a trip to Iowa next month. But why should liberals trust him to be out for anything more than his own ego?

And why should New Yorkers trust his claims that this is really about serving them better?

With his trademark sanctimony, the mayor told Politico last week, “If the [Democratic] Party does not bring the progressive wing in more fully, then it’s at the party’s peril. I think there was a huge mistake made in 2016 to not invite in the Bernie Sanders movement more effectively.”

That’s what the Bernie Bros think. But they also know de Blasio spent the last election cycle scheming to win a high-profile spot with Team Hillary.

Remember, the WikiLeaks dumps of Clintonite e-mails didn’t just expose how Hillary’s people used the Democratic National Committee to sabotage the Sanders campaign: They also showed top aides such as Huma Abedin and John Podesta fending off the mayor’s demands for a prominent role in exchange for his endorsement.

Back in November 2014, Abedin complained of de Blasio’s push for “increased direct access to [Clinton] so he can tell his progressive partners what she thinks about issues important to them … He wants to be seen as the loudest progressive voice for her and in order to do that he needs access.”

But Abedin wanted “someone else” to “inherit this relationship” because giving in to the mayor “will not be tenable for HRC.”

Then there was the April 2015 presidential forum that de Blasio wanted to moderate in Iowa. Podesta e-mailed Clinton staffer Neera Tanden, “Should we care about this?” She replied, “Politically, we are not getting any pressure to join this from our end . . . I’m not sweating it.” De Blasio wound up having to cancel the event because Bernie wouldn’t go either.

Yet Blas kept playing hard-to-get in public. In June he said, “I’m waiting to hear . . . [Clinton’s] larger vision to addressing income inequality” and “I’ve always liked what I heard from Bernie Sanders.”

That prompted Hillary campaign manager Robby Mook, who knew all about the mayor’s secret push for a top role in her campaign, to joke, “What a terrorist.” Communications chief Jennifer Palmieri responded, “Told you!” — because she had distrusted de Blasio all along.

By September, the mayor was e-mailing Podesta and Mook that, if asked about his non-endorsement, “I will . . . have lots of praise for Hillary and her increasingly clear, strong agenda. Will say her campaign is doing much better than the conventional wisdom recognizes.” But he would also “praise Bernie’s ideas if asked.”

The Clintonites kept refusing to promise him anything, and de Blasio finally endorsed her anyway the next month.

Once on board, he was perfectly willing to lie for Hillary, saying on “Morning Joe” that “I don’t care about [Clinton’s paid, secret Wall Street] speeches” — even as he was telling Podesta, “This one is hard to defend.”

De Blasio’s machinations, in short, look nothing like what he described last week at Medium.com: “I cannot separate my concept of how to be an effective public servant from my faith in the power of organizing and activism.”

‎Heck, he even admitted to Politico that his new national act will require him to create his own political action committee. His team won’t even rule out again taking donations from people with business before the city — when selling City Hall access to fund his personal political ambitions landed de Blasio in major state and federal criminal investigations. Hey, he avoided prosecution then, so why not do it all over again?

He’s just shameless.