Meet the longshot candidates who could swing the 2024 election

Sixteen people are running to become president of the United States in 2024 - but not all are Democrats or Republicans.

Three candidates are running on their own or with a third party, and a fourth could soon join their ranks.

None are considered serious contenders for the White House.

Still, they all have the potential to siphon off support from President Joe Biden, the presumptive Democratic nominee, in what may be a narrow presidential race.

Whoever wins the Republican nomination could also have to contend with these longshot outsiders, as well. Opinion polls show former President Donald Trump is currently on track to become Republicans' nominee.

Let's have a look at the independent and third-party candidates and the possible threats they pose.

As a nephew of former president John F Kennedy Jr, the 69-year-old is a scion of America's most famous political dynasty and a controversial anti-vaccine activist.

Mr Kennedy, a former environmental lawyer, entered the presidential race as a Democrat earlier this year. That changed in October when he declared he would challenge what he called the "two-headed monster" of the US political system as an independent.

"The Democrats are frightened that I'm going to spoil the election for President Biden," he said at a rally in Philadelphia. "The Republicans are frightened that I'm going to spoil it for President Trump. The truth is, they're both right."

On the campaign trail, Mr Kennedy has come under intense criticism for repeating debunked conspiracy theories, such as a connection between childhood vaccines and autism.

He has also repeatedly condemned steps taken to mitigate Covid-19, in one instance likening vaccine mandates to Nazi Germany. He later apologised.

While he stands little chance of success at the polls, Mr Kennedy's populist economic message has won over many voters.

One national poll - conducted by Quinnipiac University - found that Mr Kennedy could receive as much as 22% of voters in a three-way match-up with Mr Biden and Mr Trump.

Another recent poll from the New York Times and Siena College, suggested that Mr Kennedy has more support among young Americans in several critical battleground states than both leading party candidates.

A well-known and outspoken progressive activist and academic, 70-year-old Mr West is currently a professor of philosophy at Union Theological Seminary in New York City. He previously taught at Yale, Princeton and Harvard.

Mr West launched his presidential bid in June as a candidate for the People's Party, a self-described progressive group created by people who once worked for Bernie Sanders, one of only three independents in the US Senate.

In a campaign video posted online, he vowed to run "for truth and justice" and criticised both parties for not "telling the truth"

Soon after, Mr West said that he would also seek a nomination from the Green Party.

But he too reversed course and in October announced that he would run as an independent candidate. His campaign has largely focused on a socialist platform that has included public healthcare and slashing the US defence budget.

While Mr West has largely been ignored by the other candidates and most polls show him having support in the single digits, some data has suggested that his candidacy has siphoned off some voters - 1 or 2% - from Mr Biden.

On 9 November Ms Stein, a 73-year-old activist and physician, announced that she would run for office and again seek the Green Party's nomination. She unsuccessfully ran as the party's candidate in 2012 and 2016.

Ms Stein announced her candidacy in a video attacking both political parties as posing a "danger to our democracy".

"Democrats have betrayed their promises for working people, youth and climate again and again," she said. "Republicans don't even make such promises in the first place."

In the video, Ms Stein also called for an "economic bill of rights" that would include universal access to healthcare and education and a right to employment. She also vowed to fight climate change and the rights of women seeking abortions and the transgender community.

It is unclear how much support she could siphon off from Mr Biden - but she has been a spoiler in the past.

In the 2016 presidential election, 1.6 million Americans voted for her. Some Democrats blamed her for taking support from Hillary Clinton in key battleground states and ultimately helping Mr Trump win.

In three of these states - Pennsylvania, Michigan and Wisconsin - Ms Clinton lost to Mr Trump by fewer votes than Ms Stein received.

The Green Party, whose nominee will be confirmed at a convention next year, is on the ballot in 17 states, according to its official website.

There's another possible wrench that could be thrown into 2024 election: the "No Labels" movement.

The movement, first launched in 2010, is "preparing for the possibility of nominating a candidate", although it has "not yet committed to do so", according to its web site.

Speculation is building about who it is preparing to possibly nominate after West Virginia Senator Joe Manchin, a moderate Democrat, announced he would not run for re-election.

Manchin, who has described himself as "centrist, moderate, conservative Democrat", headlined an event for the organisation in July, alongside former Utah Governor Jon Huntsman, a Republican, and has been involved with it since its first meeting.

Aimed at supporting centrism in American politics, the well-funded group bills its platform as a "policy for America's common sense solutions" that is focused on listening "to the majority of Americans and less to extremists on the far left and right".

It 67-page policy position document presents those solutions for a wide range of issues. On gun safety, for example, the organisation says that, while Americans have a constitutional right to own firearms, society has "a responsibility to keep dangerous weapons away from dangerous people".

Senior Democrats are very wary of any No Labels candidate.

Mr Biden said in an interview with ProPublica that he believes the group will "help the other guy" - a reference to Mr Trump.

Meanwhile, former House Speaker Nancy Pelosi has accused the group of being "perilous" to US democracy.

Another Democrat, former House Majority Leader Dick Gephardt, has started a political action committee - Citizens to Save Our Republic - with the express aim of raising money to fight No Labels and get the group to "stand down".