https://www.wsj.com/articles/a-winding-constitutional-path-from-trump-to-pence-to-pompeo-11601677891?mod=opinion_lead_pos8
What if President Trump becomes seriously ill and unable to do his job? Under the 25th Amendment, the president can report to Congress that “he is unable to discharge the powers and duties of his office.” Vice President Mike Pence would become acting president until Mr. Trump sends a second written declaration that he can perform his duties again.
But suppose he’s unable or unwilling to issue the declaration. The 25th Amendment provides for that too. If the vice president and a majority of “the principal officers of the executive branch”—defined by statute to include the heads of the 15 major executive departments—declare in writing that the president “is unable to discharge the powers and duties of his office,” Mr. Pence becomes acting president “immediately.”
Mr. Trump’s opponents have often mused about invoking the 25th Amendment to remove him from office for behavior they regard as erratic. The idea reflects a misunderstanding of how the amendment works. Even in the unlikely event that Mr. Pence and the cabinet backed such a move, the president could challenge it. The disagreement would be resolved in the president’s favor unless two-thirds of both houses of Congress overrode him—and even then, his removal would be temporary. The 25th Amendment deals with cases of genuine debility, such as might arise if the president became seriously ill.
Mr. Pence has tested negative for the coronavirus. But suppose that changes and both he and Mr. Trump are too sick to perform the presidency’s duties. Article II of the Constitution states that in “the case of removal, death, resignation or inability” of both the president and vice president, Congress has the authority to declare “what officer shall then act as president” until the disability ends or a new president is elected. The term “officer” poses a problem for the current law.