When Richard Nixon took office in 1969, he, too, went gunning for holdover US attorneys.

Just as now, Manhattan’s US attorney was asked to resign.

And just as now, he refused.

“I had a couple of cases I wanted to finish,” then-US Attorney Robert Morgenthau recalled to The Post Saturday.

Those cases included investigations into Nixon campaign donors, making the Democratic Morgenthau a sizeable thorn in the new Republican administration’s side.

But while President Trump had the power to summarily fire Preet Bharara as prosecutor, as he did Saturday, back then, a president could only fire a US attorney for cause.

Why didn’t Nixon try to cook something up?

“You’ve gotta ask him,” Morgenthau, 97, joked by phone from his family apple farm in southern Dutchess County.

“But I think you’d have to use a special phone.”

Morgenthau wound up staying put a year before stepping down. He’d later serve as the Manhattan district attorney.

Of Trump’s US attorney purge, he said, “My concern is with making this a political football.”

“What happens to the pending investigations? Are they completed or left up in the air? Will the new appointees demand everybody’s resignation? This shouldn’t depend on a political whim.”