The Bernie Sanders candidacy didn’t die a natural death — it was murdered. And the murder weapon has the fingerprints of the Washington Post all over it.

That’s the contention of the much-respected progressive writer Thomas Frank (author of the beloved-by-the-left book “What’s the Matter With Kansas?”) in an evisceration of the media’s role in taking down Sanders that will be the cover story of the November issue of Harper’s.

Frank went through every one of hundreds of opinion pieces published in the Washington Post on Sanders and Hillary Clinton, his rival for the Democratic nomination for president, during primary season, from January to May 2016, and found a stark disparity in coverage. Sanders pieces took a negative tone by a ratio of 5 to 1, whereas opinion pieces on Clinton were about evenly split between favorable and unfavorable.

Newspapers can take whatever editorial stance they wish, but Frank sees in the Washington Post the epitome of Beltway bluestocking insider liberalism — pro-Wall Street, globalist, technocratic and white-collar. The vehemence with which these writers denounced Sanders suggested to Frank a primal loathing: “In Bernie Sanders and his ‘political revolution,’ on the other hand, I believe these same people saw something kind of horrifying: a throwback to the low-rent Democratic politics of many decades ago … to the affluent white-collar class, what he represented was atavism, a regression to a time when demagogues in rumpled jackets pandered to vulgar public prejudices against banks and capitalists and foreign factory owners. Ugh.”

Frank cites headlines that ran over opinion pieces that said things like, “NOMINATING SANDERS WOULD BE INSANE” (days before the Iowa caucuses) and “A CAMPAIGN FULL OF FICTION” (the same week). Columnist Charles Lane ridiculed Sanders for suggesting that he was fighting against “the billionaire class” that largely seems comfortable with a Hillary Clinton presidency while other writers castigated Sanders for lacking a serious plan to tackle the deficit (as though Hillary Clinton has one either).

Sanders’ anti-TARP stance, though it resonated with millions of Americans, struck the WaPo opinion writers as nuts. Where, asks Frank, was the bailout for ordinary homeowners? “Instead, Main Street America saw trillions in household wealth disappear” while the big banks were made whole.

Sanders, Frank believes, just couldn’t catch a break from the political class’s hometown bulletin. “On and on it went, for month after month, a steady drumbeat of denunciation. The paper hit every possible anti-Sanders note, from the driest kind of math-based policy reproach to the lowest sort of nerdshaming — from his inexcusable failure to embrace taxes on soda pop to his awkward gesticulating during a debate with Hillary Clinton.”

Do elite Ivy League-educated pundits such as those who write editorials and op-eds for the Washington Post even care about the striving classes beneath them? About stagnating wages and outsourced jobs? To Frank, Sanders never got a fair hearing from the liberal press about his ideas. “Rather than grapple with his ideas,” he writes, “they simply blew the whistle and ruled them out of bounds.”