 -- Bernie Sanders descended upon Washington Square Park in Manhattan's Greenwich Village Wednesday night for one of his campaign's largest, outdoor rallies.

The Sanders campaign estimated that more than 27,000 people attended the rally, making the event the campaign's third-largest rally, behind Portland, Oregon, and Los Angeles. The NYPD would not verify the number of attendees.

The crowd -- largely comprised of young people -- filled the park and crowded the adjacent streets. Many people -- visible from the windows -- also viewed the rally from apartments and New York University buildings surrounding the park.

Speakers included actress Rosario Dawson and filmmaker Spike Lee, both of whom are native New Yorkers.

"We have an opportunity with our vote on Tuesday to recognize the invisible," Dawson told the crowd of thousands, taking jabs at Sanders rival Hillary Clinton, as well. "Too many people have died for the right to vote, and too many people have died because of who is currently running."

Sanders was optimistic about a win, telling the crowd, "Two polls have us ahead of Hillary Clinton, and we are beating Trump by double digits."

He argued his campaign is the one with the momentum and that he is confident his campaign would win Tuesday's New York primary. Later in his speech, though, he hedged that prediction slightly. He said it will be a “tough race” due to the state's closed primary system, as well as Clinton’s history in the state. But he concluded that his large crowds would translate to “a surprise for the establishment."

“We have a system here in New York where independents can’t get involved in the democratic primary,” he said. He lamented the fact that New York voters had to switch party affiliations last October and new registrations had be to completed by the end of March. “Where young people who have not previously registered and want to register today just can’t do it. So this is going be a tough primary for us.”

A native New Yorker, Sanders talked about growing up in Brooklyn as the son of immigrants. He zeroed in on famous New York landmarks like the Stonewall Inn, a gay bar on nearby Christopher Street, just blocks from the rally site, which is perceived as the location of the birth of the LGBT rights movement, following police raids in the 1960s.