Here’s what happens if President Trump gets too sick to govern

(CNN) — President Donald Trump on Friday night remained in a military hospital after he and first lady Melania Trump tested positive for COVID-19.

Here’s what happens if he begins to show symptoms and gets too sick to fulfill his role as president.

The Constitution lays out rules for succession

When Boris Johnson, the British prime minister, was hospitalized with COVID-19 this year, it underscored that there was no formal succession procedure in the United Kingdom and raised serious questions about who was leading the country. Johnson called on his foreign secretary to be deputized if he was fully incapacitated.

In the U.S., there are specific guidelines both in the Constitution and in federal law that dictate who takes over if Trump can’t do his work. (Here’s the line of succession.) But the first step is determining that a president is incapacitated — and on this point there is very little clarity.

According to the 25th Amendment, he could make that determination himself and, with a letter to the Senate, formally hand power to Vice President Mike Pence, who would then govern until Trump informed the Senate that he was taking power back.

Here’s how that looks in the 25th Amendment:

“Whenever the President transmits to the President pro tempore of the Senate and the Speaker of the House of Representatives his written declaration that he is unable to discharge the powers and duties of his office, and until he transmits to them a written declaration to the contrary, such powers and duties shall be discharged by the Vice President as Acting President.”

Ronald Reagan did this when he had cancerous polyps removed from his colon and George W. Bush did it twice when he had colonoscopies. In both cases, when the presidents were under anesthesia, they handed over power for a few hours, although Reagan disputed it was an intended use of the 25th Amendment.

The New York Times reporter Mike Schmidt recently reported that Pence was on standby to temporarily assume the powers of the presidency in 2019, when it was possible Trump would have to undergo a procedure requiring anesthesia at Walter Reed hospital, although very little is known about that situation and the White House has been guarded about details.

The Cabinet can step in

There is another clause in the 25th Amendment that’s worth considering. If the president were incapacitated to such a degree that he could not temporarily transmit power, the vice president and a majority of the Cabinet could, technically, take it from him. If the vice president and a majority of the cabinet disagree, a supermajority of Congress and the Senate could vote to take it from him permanently.

This clause had in mind a president who was in a coma or suffered a stroke.

The Reagan administration drafted, but did not sign or transmit, letters to the Senate that would have taken power from Reagan after he was shot in 1981. You can see them at the Reagan Library’s website.

Dwight Eisenhower, for instance, suffered a debilitating heart attack while in office in the 1950s. That was before the 25th Amendment, so there was no constitutional rule. Instead he came to an agreement with Vice President Richard Nixon about handing over power.

What if many people in the line of succession get sick?

The other element to consider is that since COVID-19 has infiltrated the White House, it’s possible, although not likely, the virus could incapacitate multiple members of the administration. Trump has been in close contact with Pence and Treasury Secretary Steven Mnuchin, who has been in contact with House speaker Nancy Pelosi.

His Supreme Court nominee, Amy Coney Barrett, has been working out of the White House and traveling to Capitol Hill to meet with senators.

The Presidential Succession Act is a law that’s been in place since 1948 and it lays out a very long line of succession for the presidency “If, by reason of death, resignation, removal from office, inability, or failure to qualify, there is neither a President nor Vice President to discharge the powers and duties of the office of President.”

First up is speaker of the House, although he or she would have to resign from Congress. Then comes the most senior U.S. senator. Then it moves to the Cabinet.

And beyond plans for succession, the U.S. has gamed out plans to keep the government functioning — it’s called continuity of government — in all sorts of eventualities.

Obama administration Department of Homeland Security official Juliette Kayyem said on CNN Friday that people should not worry about the government failing to function.

“Given the likelihood that statistically that the Trumps will be OK, they might be out of commission for a couple days. I think the consequences will be more political than anything else,” she said, pointing to the contingency of government planning.

“The systems are in place, they appear to be working. You’re nervous because this is a time to be nervous, but in terms of the fact that Trump is not the presidency, nor is he the United States, we have plans for whatever contingency may occur.”

What about the election?

One contingency that would be unprecedented in modern times is if a presidential nominee gets too sick to carry on a campaign.

Both Trump and his Democratic rival Joe Biden are on the ballot. People are already voting by mail and absentee, and the election will go ahead as planned.

The-CNN-Wire™ & © 2020 Cable News Network, Inc., a WarnerMedia Company. All rights reserved.