Bernie Sanders’ refusal to give up and go away has the Democratic establishment in a swivet. It’s gotten to the point that even lefty outlets like The Nation are turning critical — fearing that continued division could hand the White House to Donald Trump.

Sorry, Democrats, you have only yourselves to blame — for trying to turn the primaries into a coronation march for Hillary Clinton. Too many voters wanted some other choice, and Sanders became their vehicle.

The party’s leaders and big donors united behind Clinton early on, muscling out other top names like Joe Biden and Liz Warren. No one expected a socialist in his 70s to pose a real challenge — until he did.

The party’s left — far larger after two Obama terms — doesn’t trust Clinton. The memories of Bill Clinton’s neither-right-nor-left “triangulation” are too deep; the Clintons’ feeding at the Wall Street trough too massive and too recent.

Actually, lots of Democrats don’t trust her: Many Sanders voters don’t “feel the Bern,” they’re just voicing dissent against the inevitable nominee.

She is, after all, a rotten candidate — painfully stiff when reading her script, prone to massive gaffes (“We’re going to put a lot of coal miners . . . out of business”) when she’s not.

Her weaknesses are surely one reason the party’s chief, Debbie Wasserman Schultz, did her best to shield Clinton — scheduling debates to minimize viewership, even briefly shutting down the Sanders campaign’s access to its own voter database.

Oh, and setting up a “joint” fundraising arm that, by “maxing out” donors, has reduced other Democrats’ power to fund their own races this fall.

Well, the Democratic establishment went all-in for Clinton, and it’s going to get what it wished for: The polls now suggest she’ll win California and New Jersey come June 7, giving her the nomination without using superdelegates.

But that’s no reason for Sanders to quit yet: Back in 2008, Clinton took her fight against Barack Obama all the way to June.

And Hillary wasn’t pulling her punches then the way her supporters are pushing Bernie to do now: They even had Bill play the race card.

That’s the Clintons for you, yet again: It’s one set of rules for everyone else — another set for them.