Related video: Trump polls far ahead of Republican rivals, despite legal troubles
The 2024 election looks set to be a rematch between President Joe Biden and his predecessor Donald Trump.
Despite his mounting legal problems, Mr Trump is by far the most popular candidate in the Republican field.
Only Florida governor Ron DeSantis has reached double digits but he remains miles behind Mr Trump.
Author Marianne Williamson and anti-vaccine conspiracy theorist Robert F Kennedy Jr are challenging Mr Biden for the Democratic nomination but they are not considered real threats to the president.
Mr Trump was indicted for the third time on 1 August for his efforts to overturn the 2020 election. As Democrats coalesce behind Mr Biden, Mr Trump’s mounting legal woes appear to only strengthen his support with his base.
The Republican primary is scheduled to begin with the Iowa caucuses on 15 January and the New Hampshire primary on 23 January. The primary season may go all the way into June, but who the nominee is expected to become clear well before that point.
