Early morning on October 2nd, President Trump revealed that he and the first lady, Melania Trump, had tested positive for COVID-19. The news threw the nation’s leadership into question and shocked the public: the coronavirus pandemic, which has affected the United States since early March (with over 27,000 deaths), had reached the White House.

President Trump’s tweet revealing the news around 1 a.m. ET Friday prompted numerous questions from within and outside the White House. What would happen to the election on Nov. 3rd, less than a month away? And more immediately, what would happen if President Trump became too sick to fulfill his presidential duties?

It is unlikely that the election on Nov. 3rd would be postponed or delayed. The United States has never postponed an election before, and it would be difficult to do so. By Constitutional law, Congress has the power to determine election day, and it has always been the first Tuesday after Nov. 1st. In order to change election day, the House (majority Democratic) and the Senate (majority Republican) would need to agree on changing the law. At present, this is extremely unlikely given the partisan divides.

This is not the first time the President of the United States’ health has been called into question. In 1919, President Woodrow Wilson caught influenza during peace talks at the end of World War I and suffered a stroke. In his case, his wife took over much of the White House’s business while he was bed-ridden, but there was no true “successor”.

In the case of a President’s death, the Vice President is sworn into office. The most famous example of this is after President John F. Kennedy’s assassination in 1963. The Vice President at the time, Lyndon B. Johnson, was sworn into office aboard Air Force One while standing next to first lady Jacqueline Kennedy.

After JFK’s assassination, the 25th Amendment (ratified in 1957) clarified the line of presidential succession. The 25th Amendment has since been used once by President Reagon and twice by President Bush, both briefly handing power to their Vice Presidents before undergoing surgery.

Should President Trump need make use of the 25th Amendment, the first five people that stand in line for succession are: Mike Pence (Vice President), Nancy Pelosi (Speaker of the House of Representatives), Chuck Grassley (President pro tempore of the Senate), Mike Pompeo (Secretary of State), and Steve Mnuchin (Secretary of the Treasury).

President Trump or his cabinet would also need to write a letter to Nancy Pelosi and Chuck Grassley, informing both sides of Congress that he’s unable to perform his presidential duties. At that point, Vice President Mike Pence would become the acting president. Once President Trump was deemed fit for office again, he would need to address Congress in another letter to be reinstated.