Section 4: Declaration by vice president and cabinet members of president's inability
Section 4. Whenever the Vice President and a majority of either the principal officers of the executive departments or of such other body as Congress may by law provide, transmit to the President pro tempore of the Senate and the Speaker of the House of Representatives their written declaration that the President is unable to discharge the powers and duties of his office, the Vice President shall immediately assume the powers and duties of the office as Acting President.
Thereafter, when the President transmits to the President pro tempore of the Senate and the Speaker of the House of Representatives his written declaration that no inability exists, he shall resume the powers and duties of his office unless the Vice President and a majority of either the principal officers of the executive department[note 1] or of such other body as Congress may by law provide, transmit within four days to the President pro tempore of the Senate and the Speaker of the House of Representatives their written declaration that the President is unable to discharge the powers and duties of his office. Thereupon Congress shall decide the issue, assembling within forty-eight hours for that purpose if not in session. If the Congress, within twenty-one days after receipt of the latter written declaration, or, if Congress is not in session, within twenty-one days after Congress is required to assemble, determines by two-thirds vote of both Houses that the President is unable to discharge the powers and duties of his office, the Vice President shall continue to discharge the same as Acting President; otherwise, the President shall resume the powers and duties of his office.[5]
Section 4 addresses the case of an incapacitated president who is unable or unwilling to execute the voluntary declaration contemplated by Section 3. It allows the vice president, together with a "majority of either the principal officers of the executive departments or of such other body as Congress may by law provide",[note 2] to issue a written declaration that the president is "unable to discharge the powers and duties" of their office. Immediately upon such a declaration being sent, the vice president becomes acting president[note 3] while (as with Section 3) the president remains in office, albeit divested of all authority.[7]
John Feerick, the principal drafter of the amendment,[6]:5[8][3]:xii,xx writes that Congress determined that "a rigid constitutional definition [of the terms unable and inability] was undesirable, since cases of inability could take various forms not neatly fitting into such a definition ... The debates surrounding the Twenty-fifth Amendment indicate that the terms unable and inability are intended to cover all cases in which some condition or circumstance prevents the President from discharging his powers and duties ..."[3]:112 A survey of scholarship on the amendment found:
no specific threshold – medical or otherwise – for the "inability" contemplated in Section 4. The framers specifically rejected any definition of the term, prioritizing flexibility. Those implementing Section 4 should focus on whether – in an objective sense taking all of the circumstances into account – the President is "unable to discharge the powers and duties" of the office. The amendment does not require that any particular type or amount of evidence be submitted to determine that the President is unable to perform his duties. While the framers did imagine that medical evidence would be helpful to the determination of whether the President is unable, neither medical expertise nor diagnosis is required for a determination of inability ... While foremost in [the minds of those who drafted Section 4] was a physical or mental impairment ... Section 4 sets forth a flexible standard intentionally designed to apply to a wide variety of unforeseen emergencies.[6]:7,20
Among potential examples of such unforeseen emergencies, legal scholars have listed kidnapping of the president and "political emergencies" such as impeachment. Traits such as unpopularity, incompetence, impeachable conduct, poor judgment, or laziness might not in and of themselves constitute inability, but should such phenomena "rise to a level where they prevented the President from carrying out his or her constitutional duties, they still might constitute an inability, even in the absence of a formal medical diagnosis." In addition, a president who already manifested disabling traits when he or she was elected is not thereby immunized from a declaration of inability.[6]:21n63,22n67
The real issue I suppose would be that there is a longer period where Congress is involved that extends past the term anyways.
EDIT: I think I read it wrong? It says UNLESS Pence does the stuff within 4 days. Does Pence stay as Acting President for the 21 days Congress has to vote with a 2/3 threshold to maintain the VP as acting? If Pence is Acting President at that point, Congress can wait it out.