US president Joe Biden, who took office in early 2021, faces little opposition in his bid for the Democratic Party nomination in the 2024 presidential election.
With former president Donald Trump the frontrunner in the Republican Party's nominating race, Mr Biden's strong position in the Democratic primary sets up a likely repeat of the 2020 presidential election battle.
However, one of his Democratic challengers - Robert F Kennedy Jr - could run as an independent and play the spoiler.
Joe Biden
Mr Biden, 80, already the oldest US president ever, will have to convince voters he has the stamina for another four years in office, amid concerns about his age and poor approval ratings. Biden allies say he believes he is the only Democratic candidate who can defeat Trump.
In announcing his candidacy, Mr Biden declared it was his job to defend American democracy, and referred to the deadly January 6th, 2021, attack on the US Capitol by Trump supporters. Vice president Kamala Harris is again his running mate.
The economy will factor in his re-election campaign. While the US escaped an expected recession and is growing faster than economists expected, inflation hit 40-year highs in 2022 and the cost of food and gas is weighing on voters.
Mr Biden has led the response of Western governments to Russia's invasion of Ukraine, persuading allies to sanction Russia and support Kyiv.
At home, he has pushed through massive economic stimulus and infrastructure spending packages, although he has received little recognition from voters for the latter.
Mr Biden's handling of immigration policy has been criticised by Republicans and Democrats as migrant crossings at the US-Mexico border hit record highs during his administration.
Robert F Kennedy Jr
An anti-vaccine activist, Robert F Kennedy Jr, 69, launched a long-shot bid to challenge Mr Biden for the Democratic nomination, but he is behind and is soon expected to announce a run as an independent.
He is the son of US senator Robert F Kennedy, who was assassinated in 1968 during his own presidential bid.
Mr Kennedy was banned from Instagram for spreading misinformation about vaccines and the Covid-19 pandemic, but was later reinstated. He lost a legal bid to force YouTube owner Google to reinstate videos of him questioning the safety of Covid vaccines.
Marianne Williamson
The best-selling author and self-help guru Marianne Williamson, 71, has launched her second, long-shot bid for the White House on a platform of "justice and love".
She ran as a Democrat in the 2020 presidential primary but dropped out of the race before any votes had been cast. She launched her latest campaign on March 23rd.
