United States President Donald Trump on Friday tested positive for Covid-19 with less than five weeks left before the November 3 election. At 74, the US president is in higher-risk age group where 20 per cent of cases require hospitalisation.
The situation has raised many questions regarding the possibility of President Trump's untimely demise or his incapability to serve as the president.
Despite being unprecedented, there are established processes in the United States Constitution to tackle such a situation. Under the US Constitution's 25th Amendment: "In case of the removal of the president from office or of his death or resignation, the vice president shall become president."
According to the US Law, the 48th and current vice president of the US, Michael R Pence, will be sworn in as the President in case the coronavirus takes its dire toll on Trump or he is somehow unable to serve his position as the president.
Under the 25th Amendment, ratified to clarify presidential disability and succession planning, presidents can voluntarily designate powers to their vice presidents if they become seriously ill or are unable to perform their duties.
The Presidential Succession Act, which was enacted in 1947 after the death of President Franklin D Roosevelt in 1945, states the speaker of the House is next in line, followed by the president pro tempore of the Senate, and then members of the cabinet, starting with the secretary of state
Should Donald Trump become gravely ill, he could provide letters to the speaker of the House and the president pro tempore of the Senate saying he was "unable to discharge the powers and duties of his office" to transfer his powers to Mike Pence, who would, in effect, become acting president. Trump could reclaim his full authorities when he recovered.
Since the amendment was ratified in 1967, the vice president has taken power in only three instances, each of them exceedingly brief.
Situations when a vice president has ascended in case of the untimely demise of a president or his incapability to serve has occurred numerous times in the US's history, with vice-president George H Bush being president only for a few hours when President Regan was put under anesthesia during a medical procedure.
John Tyler - the tenth President of the US - ascended to the presidency after President William Henry Harrison died only a month after the new administration's start.
The 13th President of the US, Millard Fillmore, became the President after the death of President Zachary Taylor.
After the assassination of one of the most popular US President, Abraham Lincoln, Andrew Johnson assumed the presidency.
Chester Alan Arthur - 20th President of the US - ascended to presidency two months after an assassin shot President James A Garfield.
Theodore Roosevelt became the youngest President in US history after President McKinley's assassination.
Calvin Coolidge - 30th President of the US - assumed the presidency after the sudden death of President Warren G Harding.
Harry S Truman - 33rd President of the US - ascended to the presidency after the death of Franklin D Roosevelt.
After the infamous assassination of John F Kennedy in 1963, Lyndon B Johnson became the President.
Gerald Ford - 38th President of the US - became the only vice president to ascend as the President without having been previously voted into either the presidential or vice-presidential office by the Electoral College.
When President Ronald Reagan was put under anesthesia for a colon procedure, he granted his powers to Vice President George H Bush for about eight hours, though he avoided formally invoking the amendment.
2002 and 2007
President George W Bush temporarily transferred his authorities to Vice President Dick Cheney during colonoscopies.
If the vice president also dies or becomes incapacitated, the Constitution leaves it to Congress to decide what should happen.