Elizabeth Warren pledged to tackle corruption in Washington, DC, and enact economic reforms that would no longer enrich the wealthy and powerful during a speech on Monday.

Speaking to more than 20,000 supporters in Washington Square Park, the Massachusetts senator called for sweeping structural changes, rather than smaller fixes she claims are advocated by Democratic rivals like former Vice President Joe Biden.

“I know people are scared, but we can’t choose a candidate we don’t believe in just because we’re too scared to do anything else,” Warren said, speaking under the Washington Square Park Arch. “Democrats can’t win if we’re scared and looking backwards.”

Warren got a leg up earlier Monday when the Working Families Party endorsed her for president, despite backing fellow progressive Bernie Sanders in 2016.

Maurice Mitchell, Working Families Party national director, said Warren “strikes fear into the hearts of the robber barons who rigged the system, and offers hope to millions of working people who have been shut out of our democracy and economy.”

Warren made her pitch for “big, structural change” near the site of the Triangle Shirtwaist Factory that burned in 1911 and killed 146 people – mostly immigrant women. The fire was a turning point for union organizing and labor reforms, and Warren called for that kind of mobilization to tilt the balance of power toward the working class.

“We win when we get out there and fight. I am not afraid and you can’t be afraid either,” said Warren, who wants to enact a wealth tax to pay for her priorities.

Warren’s take-on-the-elites speech happened in the wealthy and highly educated neighborhood of Greenwich Village with a median household income of $120,000.

She touted her anti-corruption plan that would topple the way lobbying works in Washington, ban government officials from stock trading and ensure presidents don’t use the office for personal profit.

Released earlier Monday, Warren’s plan would also require the IRS to automatically publish the tax returns for all federal candidates and ban forced arbitration clauses and class action waivers that prevent employees from filing lawsuits.

“Corruption has put our planet at risk,” Warren said. “Corruption has broken our economy and corruption is breaking our democracy.”

The Warren campaign said 23,000 people RSVP’ed for the event and more than 20,000 joined — though they stopped counting when the speech started.