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 77-year-old Vermont senator became a progressive political star in 2016 although he lost his candidacy bid.
His campaign says it raised $1m (£777,000) within three and half hours of launching.
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.
His calls for universal government-provided healthcare, a $15 national minimum wage and free college education electrified young voters, raised millions of dollars in small donations and are now pillars of the party’s left wing.
Mr Sanders, who lost the 2016 Democratic primary to former Secretary of State Hillary Clinton, said in his email: “Three years ago, when we talked about these and other ideas, we were told that they were ‘radical’ and ‘extreme’.
“Together, you and I and our 2016 campaign began the political revolution. Now, it is time to complete that revolution and implement the vision that we fought for.”
Mr Trump, speaking to White House reporters on Tuesday, wished Mr Sanders well on his second bid.
“Personally I think he missed his time,” the president said. “But I wish Bernie well. It will be interesting to see how he does.”
“He ran great four years ago and he was not treated with respect by [Hillary] Clinton and that was too bad,” he added.
The president added that he liked Mr Sanders as they both have been “tough on trade”.