Four surprises that could upend the 2024 US election

A year out, and all the indications are that the 2024 election will be a re-run of 2020 but with the roles reversed - Donald Trump taking on the president, Joe Biden.

There is a widespread sense of frustration that voters have the same choice to make, and everything seems set in a familiar pattern. Even the polls seem to indicate a race that is neck-and-neck.

But as any historian will tell you, anything can happen in a year to upend the race. In 1979, a hostage crisis arguably cost President Jimmy Carter re-election. And in 2020 a pandemic reshaped the country.

Here is a look at four surprises that could change the course of this election.

What if an independent candidate gains steam?

By Katty Kay

If you aren't a Republican or a Democrat, your chances of becoming US President are smaller than slim. But third party-candidates have upended elections in the past - and they could do it again in 2024.

In 1992, wealthy businessman Ross Perot won 19 percent of all votes cast, and is often credited with costing the Republicans a presidential victory. In 2000, Green Party candidate Ralph Nader won 97,488 votes in Florida, helping to tip the swing state to George W Bush. And some say Green Party candidate Jill Stein hurt Hillary Clinton in 2016.

This election may have a similar upset. A senior American politician I interviewed this week said the low approval ratings of both President Joe Biden and Republican front-runner Donald Trump may open the door to more players, and a recent Gallup poll suggests the same.

Two independent candidates have already entered the fray. Progressive activist Cornel West, and Robert F Kennedy Jr, who recently left the Democrats.

Before he switched, polls suggested Kennedy could win the support of some 20 percent of Democratic voters. Now that he has no party affiliation, Kennedy - who appeals to conspiracy-minded voters - could also take votes away from Donald Trump.

This election is likely to be tight, so even a few votes to a third-party candidate could make a big difference.

What if one of them dies before Election Day?

By Nomia Iqbal

Yes, we hear it a lot - President Joe Biden and former President Donald Trump are old. On Inauguration Day 2025, Biden will be 82, and Trump will be 78.

There are no indications to think that either of them are in poor health, but what if something did happen to them in the run up to the election?

Well, the answer depends on when.

If they fall seriously sick or die between now and New Year's Day 2023, there are many on either side willing to compete for the nomination. But it gets more complicated as states finalise their primary ballots.

If the worst happens in mid-October 2024, their name would still be on the national ballot. According to the Constitution, you can run while dead even if you can't be sworn in.

It has happened before. In 2000, Mel Carnahan was running for the US Senate when he was killed in a plane crash on his way to a campaign event. He was elected posthumously and his widow, Jean, served until a special election was held in 2002.

If the winning candidate dies after Election Day, but before inauguration, then the VP would be sworn in instead. They would then have to nominate a VP to replace themselves - who would need to be approved by Congress.

It is hugely complicated so let's hope all candidates stay in great health!

What if a foreign war escalates?

By Barbara Plett Usher

President Biden is running for re-election beset by international crises: Russia's invasion of Ukraine and Israel's offensive against Hamas. Not to mention China's steadily increasing military pressure on Taiwan's airspace as a dangerous backdrop.

His team has tried to make political mileage out of this, portraying him as a reliable commander in chief, and he gets relatively good marks in the polls for his handling of the two hot wars.

But already there are worrying trends for the president's campaign: not least a drop in support from the crucial constituency of young Democratic voters, who are angered by Biden's strong backing of Israel as Palestinian casualties mount.

And if any of these wars spread beyond current borders - if Russia attacks a Nato member country, if armed groups allied with Iran join the Hamas fight against Israel - that would upend calculations and scramble the election year.

Would the US be drawn in from the sidelines - where it now sits with deterrent force?

Would the international chaos damage the prospects of his likely rival, Donald Trump? Or would Trump get a boost from voters fed up with funding and - possibly - again fighting in foreign wars?

Many factors are out of their control, especially in the Middle East. Not a good position for any presidential candidate to be in.

What if Donald Trump goes to prison?

By Gary O'Donoghue

The former president faces 91 criminal charges in four separate trials, which are all likely to take place next year.

The maximum potential sentences amount to hundreds of years behind bars but few legal experts think that is likely, even if convicted.

Trump's lawyers have been trying hard without success to delay the trials until after the election. They know that winning the election would probably mean a delay of four years because most legal opinion rules out prosecuting a sitting president other than by impeachment by Congress.

If he goes to prison before the election, there is nothing to say he can't still win it.

Being a convicted felon does not prevent him running in a presidential election - 100 years ago, a candidate garnered nearly a million votes from behind bars. It would clearly hamper any campaigning but polls suggest many Republican voters would not be put off.

If he were elected from prison, he might be able to pardon himself of any federal convictions but if he is jailed in one of the two state cases, he would have no power to do the same. That raises the bizarre possibility of being president while an inmate.

We are in truly unprecedented territory, and even the best legal brains in the country are scratching their heads.

- This story was first published by the BBC.