What happens if a candidate drops out of the race for the White House?

Both Democratic and Republican party rules provide that an emergency meeting will be called to find a replacement in the event of a candidate dropping out.

Hillary Clinton waves outside her daughter's apartment, after having to leave early for the 9/11 memorial service. Photo: AP

Democratic candidate Hillary Clinton's collapse and sudden departure while attending a ceremony commemorating the victims of the 9/11 terrorist attacks has caused the American public to question the former US Secretary of State's health and the possibility that she will not be able to continue the race for the White House, according to AFP.

In the US Constitution, there is no law guiding the process of handling cases where a candidate cannot continue to participate in the presidential election, so the parties will follow the regulations and choose a suitable replacement.

Section 2 of the Democratic Party's bylaws, Section 7, provides that the National Committee of the Democratic Party is responsible for nominating a new candidate to fill the vacancy. A special meeting will be called by the chairman of the committee to address the issue of the candidate, and the decision will be based on a majority vote of the members attending the meeting.

Article 9 of the Republican National Committee's bylaws states that if the presidential or vice presidential nominee is unable to continue the campaign for any reason, the party's national convention or the Republican National Committee itself will convene to find a replacement. The new nominee will have to go through state-by-state primary voting.

When the National Committee votes formally, the members of the committee representing a particular state are entitled to cast the same number of votes that state would have cast at the national convention.

In history, the only other time the Democratic vice presidential candidate, Thomas Eagleton, was forced to withdraw from the race in 1972 after admitting that he had been hospitalized for depression. At the request of then presidential candidate George McGovern, the Democratic National Committee met and elected Sargent Shriver to replace him.

The possibility of Mrs. Clinton dropping out?

Hillary Clinton (in blue) slipped outside a building in North Charleston. Photo: Reuters

According to the Telegraph, conspiracy theories about Mrs. Clinton's health have been circulating since December 2012 when she suddenly suffered a concussion and fainted during a hearing in the US Congress. She was later diagnosed with thrombosis and regularly had to take medication to thin the blood clots.

The image of the former US Secretary of State collapsing from pneumonia at the 9/11 memorial service, combined with her poor medical record, has raised many questions about who could replace her as Mr. Trump's opponent in case she had to drop out midway.

Analysts say the chances for Tim Kaine, the Democratic vice presidential candidate, are very low, while Clinton's rival, Senator Bernie Sanders, also does not have much potential.

The person most likely to replace the former US Secretary of State is Vice President Joe Biden, who was previously considered by analysts to be a possible replacement for Mrs. Clinton, as she is embroiled in legal troubles related to the leak of confidential emails from her time as Secretary of State.

However, many reputable experts still believe that the possibility of the Democratic candidate dropping out of the race for the White House due to health reasons is very low.

"If Mrs. Clinton drops out, this year's race will become a crazy election. I wouldn't be surprised, but I hope that doesn't happen," said Jeanne Zaino, a political science professor at Iona College, New York.

"I don't believe Mrs. Clinton will give up, her illness is completely curable," said David Lublin, professor of government at American University.

According to VNE