Donald Trump’s triumph over Hillary Clinton presages an even bigger battle ahead against the heart of the Democratic establishment: the federal workforce. This army of bureaucrats — almost 3 million strong — gave Clinton a large majority of their votes and over 90 percent of their campaign contributions.

Expect federal workers and their union bosses to use every trick in the book to block Trump’s reform agenda.

Trump’s ability to fix the Department of Veterans Affairs, clean up IRS abuses, roll back job-killing regulations and get taxpayers their money’s worth all hinge on uprooting the entrenched civil service. Newt Gingrich, a top Trump adviser, warns: “If you don’t fix this problem, nothing in government is going to work.”

That’s a tall order. The bureaucracy generally has a vise-like grip on the executive branch — presidents come and go, but the bureaucrats remain.

Public unions are already digging in for a fight. After the election, J. David Cox, president of the American Federation of Government Employees, dismissed Trump’s plans as more or less irrelevant. AFGE members have their own big-government agenda, and “that never changes no matter who sits in the White House.” Protection of the status quo at any cost.

Even deaths. Thousands of sick vets died at VA hospitals because of employee self-dealing. Bureaucrats doctored the medical wait lists to earn bonuses while vets languished without care.

Despite Congress enacting “reforms” and President Obama appointing a new VA secretary in 2014, the bureaucracy continues to block giving vets access to civilian care. How hard is it to fire anyone at Veterans Affairs? One surgeon found guilty of abandoning a patient on the operating table and leaving the medical center still got an $11,000 bonus.

As a candidate, Trump promised to make swift changes. Exit polls show military families voted for him 2-1 over Clinton. Dan Caldwell of Concerned Veterans for America says he’s encouraged to see civil service reform at the top of Trump’s agenda.

The same changes needed to turn around the VA have to be made across all federal departments. Right now, workers found guilty of serious misdeeds like tax evasion, watching porn on the job or fraudulent collection of unemployment benefits typically keep their jobs and get bonuses.

Firing requires so many months of documentation, hearings and appeals that bosses decide it’s not worth the trouble. No-show jobs are rampant, costing $1 billion a year. Supervisors ignore the waste and just hire someone else to get the work done.

Breaking up the federal employee protection racket will require muscle from Congress and the Department of Justice. Obama’s DOJ obstructed efforts to fire wrongdoers and incompetents. Now, with the White House and Congress under Republican control, taxpayers have a fighting chance.

A bipartisan VA reform bill with real teeth has already passed the House and is ready for Senate action. It will shorten the process for firing and demoting senior VA personnel, even eliminating appeals to the misnamed Merit Systems Protection Board, which protects criminals and dead wood, not merit.

Count on fierce opposition from union-funded pols like Sens. Bernie Sanders (D-Vermont) and Richard Blumenthal (D-Connecticut), who gutted previous efforts to hold VA employees accountable.

Will Trump, a newcomer to Washington, succeed where other presidents have failed? Possibly. He’s shown he gets his money’s worth. After all, he defeated spendthrift Clinton with less than a quarter of the campaign staff and half the spending.

But federal employees will scramble to stay on the gravy train. They earn a whopping $123,160 a year on average — about a third more than private-sector employees — get over a month’s paid vacation and don’t lose sleep over getting fired. Hard to call them civil “servants.”

Obama hiked their pay, and Clinton promised to give them even more, after which she happily received their votes. One hand washes the other. Trump understands who should be calling the shots in Washington, DC: not federal bureaucrats but the taxpayers who cover their salaries.

Betsy McCaughey is a senior fellow at the London Center for Policy Research.