Four top career officials at the State Department left the same day Secretary of State-designate Rex Tillerson paid a visit to Foggy Bottom to introduce himself, officials said Thursday.

The four — including Patrick Kennedy, State’s long-time undersecretary for management, who had been with the department since 1973 — and the others left on Wednesday.

“As is standard with every transition, the outgoing administration, in coordination with the incoming one, requested all politically appointed officers submit letters of resignation,” acting State Department spokesman Mark Toner said.

“These positions are political appointments, and require the president to nominate and the Senate to confirm them in these roles. They are not career appointments but of limited term.”

Toner went on to thank those who were canned for their service.

“These officers have served admirably and well. Their departure offers a moment to consider their accomplishments and thank them for their service,” he said.

Kennedy, a nine-year veteran in his last post, had been active in the transition from John Kerry to the former ExxonMobil chief, and was said to want to remain in the job.

The Washington Post reported that he and Assistant Secretary of State for Administration Joyce Anne Barr, Assistant Secretary of State for Consular Affairs Michele Bond and Ambassador Gentry O. Smith, director of the Office of Foreign Missions, had all resigned rather than serve under President Trump.

But a source close to the White House denied that.

“Pat Kennedy was fired. He may be saving face and pretending that he resigned but he was let go. The poorly performing senior leaders at State will also be pushed out. You should expect other ‘resignations’ there, too,” the source told The Post.

All were long-time staffers who had served under both Democratic and Republican administrations.

And they weren’t the first to go.

Assistant Secretary of State for Diplomatic Security Gregory Starr retired Jan. 20 — the day Trump was inaugurated — and the director of the Bureau of Overseas Building Operations, Lydia Muniz, left the same day.

CNN said they had all gotten letters from the White House telling them their services were no longer needed.

“It’s the single biggest simultaneous departure of institutional memory that anyone can remember, and that’s incredibly difficult to replicate,” David Wade, who served as State Department chief of staff under Kerry, told the Washington Post.

“Department expertise in security, management, administrative and consular positions in particular are very difficult to replicate and particularly difficult to find in the private sector.”

Ambassador Richard Boucher, the State Department spokesman for Colin Powell and Condoleezza Rice, said there’s always turnover when a new administration takes office and that top officials work with the new appointees to see who should stay on.

But the mass exodus will make it harder for Tillerson to hit the ground running, he said.

“You don’t run foreign policy by making statements, you run it with thousands of people working to implement programs every day. To undercut that is to undercut the institution,” Boucher said.

Meanwhile, the US Border Patrol chief has left the agency that’s in charge of securing the country’s borders with Mexico and Canada.

A current and former official told AP that Border Patrol agents had been informed that Mark Morgan is no longer on the job.

It was not immediately clear whether Morgan quit or was canned.

Morgan’s departure comes a day after Trump announced plans to build a wall at the Mexican border and hire 5,000 Border Patrol agents.