Bernie Sanders has launched his 2020 presidential campaign by calling on Americans to join his fight for a "political revolution".
The Vermont senator called Donald Trump "the most dangerous president in US modern history" at his speech at Brooklyn College in New York.
He added that Mr Trump wants to "divide us up".
Mr Sanders, who lost the race for the Democratic nomination to Hillary Clinton in 2016, said he wants to create an economy and government that works for all people.
He added that his government would focus on economic, social, racial and environmental justice.
Mr Sanders, a self-described democratic socialist, made his speech miles from the rent-controlled apartment where he grew up in Brooklyn.
He said: "My experience as a child, living in a family that struggled economically, powerfully influenced my life and my values.
