House Democrats are grilling a stream of disgruntled career diplomats in a basement hearing room of the Capitol. The hearings are supposed to be secret, but Democrats leak snippets of the testimony daily. They are hoping it will add up to a case for impeaching President Trump.

So far, all the testimony actually proves is these State Department diplomats think they, not Trump, ought to be running foreign policy. Never mind impeachment. The most pressing constitutional issue is who decides the nation’s foreign policy, the president or the permanent bureaucracy.

House Democrats are accusing Trump of offering Ukrainian President Volodymyr Zelensky a quid pro quo: dirt on Joe Biden in exchange for nearly $400 million in aid. Trump’s July 25 phone call with Zelensky is the subject of the hearings, but these witnesses have no first-hand knowledge.

Instead, they are whimpering about being sidelined by the Trump administration and objecting that top ambassadorial appointments are going to Trump’s friends instead of to them.

For example, a deputy assistant secretary named George Kent complained he was cut out of important decisions. Boo-hoo. Rep. Gerald Connolly (D-Va.) leaked Kent’s testimony, saying “here is a senior State Department official responsible for six countries” being ignored, while he watches Trump’s appointees “undermining 28 years of US policy.”

William Taylor, the acting ambassador to Ukraine who testified Tuesday, burned with indignation that Trump went “outside regular State Department channels.”

Trump’s Chief of Staff Mick Mulvaney described what’s happening: “A group of mostly career bureaucrats” refuse to accept that “elections have consequences. And foreign policy is going to change from the Obama administration to the Trump administration.”

The State Department insurrection spans embassies across the globe. On Aug. 8, Chuck Park, a foreign-service officer stationed in Mexico, penned a vitriolic public resignation for The Washington Post, condemning Trump for carrying out “mass deportations,” failing “Dreamers” and pursuing a “toxic agenda around the world.”

Two weeks later, Bethany Milton, a pro-immigration advocate and State Department official stationed in Rwanda, announced her resignation in The New York Times, scathingly labeling Trump’s foreign policy “small-minded chauvinism.”

Good riddance to Milton and Park. Resigning is what diplomats should do when they are fundamentally at odds with the administration’s foreign policy. Taxpayers shouldn’t have to foot the bill for bureaucrats intent on sabotaging the president.

Predictably, the foreign-policy establishment disagrees. William Burns, who capped his career as deputy secretary of State under President Barack Obama, argues that State Department careerists should be in charge, not the president and his appointees.

But these career diplomats favor globalism, open borders and huge American handouts to multinational organizations and Third World nations. The public elected Trump to implement the opposite. Trump must wrest control to achieve that.

Fifty years ago, Henry Kissinger understood that the diplomatic bureaucracy was biased against President Richard Nixon’s foreign-policy goals. As national-security adviser, Kissinger pulled control of diplomacy into the White House, inciting resentment and pushback from the State Department.

Again, in 2003, Newt Gingrich warned that State Department bureaucrats were engaging in “a deliberate and systematic effort” to undermine President George W. Bush. It’s happening again. The bureaucrats are slithering up to Capitol Hill to complain about Trump.

On Monday evening, House Speaker Nancy Pelosi issued a “fact sheet” about Trump’s alleged impeachable offense. It provides no damning evidence, just speculation.

On Tuesday, Taylor told the hearing that another diplomat, Gordon Sondland, had informed him Trump demanded a price for military aid to Kiev. But Sondland denies that, insisting the president made it clear there was no quid pro quo.

Too bad for the impeachment-hungry Dems and their sympathetic allies at Foggy Bottom. Disagreeing with the foreign-policy elites is not an impeachable offense. In fact, millions of Americans are cheering Trump on.

Betsy McCaughey is a former lieutenant governor of New York.