Washington (CNN) Sen. Bernie Sanders said Sunday that it is beyond his "comprehension" that the White House has not apologized in the wake of reports that a staffer mocked Sen. John McCain's health, saying "he's dying anyway," in response to the senator's opposition to President Donald Trump's pick to lead the CIA, Gina Haspel.

"It is one thing in the White House for somebody to say something crude and stupid and disrespectful about an American hero, it is another thing for them not to apologize," the Vermont independent told CNN's Jake Tapper on "State of the Union" Sunday morning.

"It is beyond my comprehension," Sanders said. "I just don't know what goes on in that White House mentality for there not being an apology for that terrible remark."

McCain is battling a brain cancer diagnosis he received last year.

CNN has reported that White House press secretary Sarah Sanders privately admonished communications and press staff on Friday over the leaked comments. Publicly, however, the White House has refused to condemn on the remark.

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