US Senator Bernie Sanders will run for President in 2020, CNN reported on Tuesday.
Mr Sanders, 77, an independent Senator for Vermont, but who votes along the Democrat line, ran for president in 2016 but was defeated by Hillary Clinton at the Democratic National Convention.
The independent candidate fought the 2016 election on a strong socialist platform, which mobilised a young left-wing base, particularly around combatting big business and social justice.
The race for the candidate to challenge US President Donald Trump in the 2020 election is starting to gather momentum, with a significant shift to the ideological left within the party.
Massachusetts Senator Elizabeth Warren, California Senator Kamala Harris and New York Senator Kirsten Gillibrand have all announced their candidacy for the Democratic nomination in 2020.
Mr Trump will also face challenges from his own party, but history shows a sitting president is highly likely to fight, and win, a second term.