With rumours circulating in recent weeks and months about the health of Hillary Clinton, many are wondering what would happen if the Democratic presidential hopeful was forced to pull out of the race, writes Greg Murphy.
Over the weekend, while attending a September 11 memorial in New York, Mrs Clinton was taken ill and escorted away from the event by her team.
It has since been revealed that the former Secretary of State was diagnosed with pneumonia last Friday by her doctor Lisa Bardack, who said she was now "recovering nicely" at home.
Republican rival Donald Trump has spent the last few months questioning her health, saying she does not have the stamina to become commander-in-chief.
Last week, while speaking at a New York rally, Mrs Clinton suffered a severe coughing fit during her speech.
With less than two months to go until the November 6 polling day, could this 'health episode' damage her chances at becoming president?
And what happens if she is forced to withdraw from the race?
The Democratic National Convention has a contingency plan in place, should a candidate drop-out before polling day.
According to Article 2, Section 7 of the DNC Bylaws a meeting will be called by the Chairperson of the Committee to choose a new candidate, based on decisions made by the majority in attendance.
This new candidate then goes on to contest the election for President of the United States.
If Mrs Clinton gets elected on November 6 but is forced to withdraw before being sworn in on January 20, things get more complicated.
The nature of US Presidential Elections means that rather than winning by a popular vote, a candidate must secure a majority of 'electoral college votes' to become president.
Each State is awarded a specific number of electoral college (EC) votes. If a candidate wins the popular vote in a state, he/she receives the EC votes from that state.
The Electoral College is the body that represents the states - it consists of 538 electors from all over the US. A majority of 270 electoral votes is required to elect the President.
If Mrs Clinton withdraws from the process after she wins election, but before the Electoral College meets, her pledged electors will be free to vote for whomever they choose.
If she becomes incapacitated between the meeting of electors and counting of EC votes in Congress, a grey area can arise as the Constitution is silent on whether or not she meets the definition of 'President elect' in that scenario.
However, should Mrs Clinton receive a majority of EC votes and be considered President elect, section 3 of the 20th amendment comes into effect.
The 'Vice President elect' - Senator Tim Kaine in this instance - would become president if Mrs Clinton withdraws from the race at this stage.
This is also the procedure should she withdraw between any of the relevant counting stages - including the electoral college and the congressional vote - and her inauguration in January.
Next in line?
Likely favourites to replace Mrs Clinton - should she be forced to withdraw - have been suggested as far back as the primary elections.
Her democratic rival Senator Bernie Sanders and current US vice president Joe Biden lead the list of potential candidates should she withdraw.
Some doubt has been cast over Bernie Sanders’ selection as he has since left the Democratic party, and is now an Independent member of the Senate.
No special privilege will be given to Vice Presidential hopeful Tim Kaine, who will remain in his current role unless chosen by the DNC to replace Mrs Clinton.