New York Mayor Bill de Blasio has announced his run for the presidency, the latest Democrat to enter the race.
In a video released on Thursday, Mr de Blasio said it was "time we put working people first" and said President Donald Trump "must be stopped".
"I'm a New Yorker, I've known Trump's a bully for a long time," he added. "I know how to take him on."
He is expected to visit Iowa and South Carolina to begin campaigning this weekend.
Mr de Blasio is the latest of more than 20 people to officially declare their candidacy to become the Democrat's presidential nominee and challenge President Trump in 2020.
But the Manhattan-born politician is no stranger to crowded races, beating out eight other Democratic contenders in his mayoral primary.
The 58-year-old progressive politician won a landslide victory in 2013 to become New York's first Democratic mayor since 1993.
Previously serving on the city's council and as New York Public Advocate, Mr de Blasio has implemented a programme of free universal pre-school, made police wear body cameras and highlighted economic inequality in the most populous city in the US.
In 2017 he was re-elected in another landslide, winning more than 66% of the vote against his Republican challenger.