Like two US presidents before him, Donald Trump could temporarily hand over power to his vice president should he become incapacitated, for example while undergoing a medical procedure as treatment for the coronavirus.
Mr Trump has tested positive for Covid-19 and is in quarantine as he begins the recovery process. Under Section 3 of the US Constitution's 25th Amendment, adopted in 1967 following the 1963 assassination of President John F Kennedy, President Trump could declare in writing his inability to discharge his duties.
Vice President Mike Pence would become acting president, although Mr Trump would remain in office. The president would regain his powers by declaring in writing that he is again ready to discharge them.