US Senator Bernie Sanders says he will run again for president in 2020, making a second attempt to win the Democratic Party's nomination, the BBC reports.
The 77-year-old Vermont senator became a progressive political star in 2016 although he lost his candidacy bid.
In an email to supporters, he said it was time to complete the "political revolution" they had started.
An outspoken critic of President Donald Trump, Mr Sanders has described him as a "pathological liar" and "racist".
Mr Sanders - an independent who caucuses with the Democrats - is one of the best-known names to join a crowded and diverse field of Democratic candidates, and early polls suggest he is far ahead.