Journalist Carl Bernstein, who knows problematic presidents, warns that we are in the midst of a “malignant presidency” the likes of which America has never before experienced.

“That malignancy is known to the military leaders of the country. It’s known to the Republican leadership in Congress who recognize it, and it’s known to the intelligence community,” the celebrated Watergate reporter noted Friday on CNN’s “New Day” program.

“The presidency of Donald Trump is not functioning,” he added. “It’s not functioning partly because of his character ... the character and capability of this president are called into grave question [and] those who know him best are raising serious concerns.”

That has “our leaders worried,” Bernstein added. “They are worried about his character. They are worried about his capabilities. They are worried about his temperament and state of his temperament — to use kind words here.”

It’s difficult to know what to do, Bernstein acknowledged because we’re in “foreign territory,” he said.

“We have never been in a malignant presidency like this before. It calls on our leaders, it calls on our journalists to do a different kind of reporting, a different kind of dealing with this presidency, and the president.”

Bernstein called it the “greatest journalistic challenge of the modern era,” to report on a “malignant presidency and what it means and where it’s going.”