Left-leaning organizations say that more than 500,000 people are expected to take to the streets to protest in Washington DC, Florida and elsewhere around the country on Saturday to oppose Donald Trump’s “authoritarian overreach and billionaire-backed agenda”.

MoveOn, one of the organizations planning the day of protest they’re calling Hands Off along with dozens of labor, environmental and other progressive groups, said that more than 1,000 protests are planned across the US, including at state capitols.

“This is shaping up to be the biggest single-day protest in the last several years of American history,” Ezra Levin, a founder of Indivisible, one of the groups planning the event, said on a recent organizing call.

The largest event is expected to be on the National Mall in Washington DC, where members of Congress, including the Democrats Jamie Raskin of Maryland, Maxwell Frost of Florida and Ilhan Omar of Minnesota, are scheduled to speak to crowds.