Perhaps the most significant Tribeca Film Festival award is that given by the audience. And so it is time to pay attention to “Street Fight,” the first full-length documentary by Brooklyn’s Marshall Curry, which took home the audience award Saturday night at the closing ceremonies of the festival.

Three years ago, Mr. Curry set out with his camera to follow Cory Booker campaigning for mayor of Newark. Mr. Curry, who accumulated more than 200 hours of footage in two months, couldn’t have dreamed up a more compelling subject. A Rhodes scholar educated at Stanford and Yale Law School, Mr. Booker went to Newark to bring equal opportunity to the city’s most impoverished citizens. He took an apartment at Brick Towers, a public-housing complex, and won a seat on the City Council before taking on a four-term incumbent, Sharpe James, in the mayoral race of May 2002. He lost by 3,500 votes.

Neither Mr. Curry nor Mr. Booker stood still for long. Mr. Booker has continued his crusade for reform in Newark and is running for mayor in 2006. (Mr. James has not said if he will run again.)

Mr. Curry, meanwhile, secured the backing he needed to complete the film, and then he achieved the Holy Grail of documentary filmmaking: being picked up by the PBS documentary series “P.O.V.” It airs nationally July 5.

Many wondered if “Fahrenheit 9/11” would help Senator Kerry’s bid for president. Mr. Curry’s film is a more direct boost for Mr. Booker’s political ambitions, though, as Mr. Curry noted, only “P.O.V.” has the right to screen it.

Showing the candidate strategizing with his staff or making door-to-door visits with voters in housing projects, the film captures Mr. Booker’s idealism and passion, and, equally important, the idealism and passion of his staff members and supporters. Their spirit is even more impressive considering how the opposition acted: The documentary depicts Mayor James as a liar and bully. Owners of businesses displaying Booker signs are told they may be shut down. Residents of public housing are told they may lose their apartments.

On Election Day, when both Mr. James and Mr. Booker have a mix of volunteers and paid workers on the streets, Mr. James tells a film crew that his “volunteer army” is up against Mr. Booker’s “paid army.”

And then there were the racial, religious, and political accusations. During the campaign, Mr. James described Mr. Booker as white, Republican, and Jewish. Mr. Booker is black, a Democrat, and Baptist.

“Street Fight” could leave the viewer sour on politics, but as the film concludes it’s clear that Mr. Curry is still rooting for the underdog to win – and that we should too. In an editorial the day after the election, The New York Sun, too, chose to look on the bright side: “If his supporters resist discouragement and remain dedicated to political reform and civic improvement, Mr. Booker’s campaign will be remembered for years to come as a victory.”

With Mr. Booker’s 2006 campaign in full swing, “Street Fight” is the ultimate campaign gift, one likely to energize Mr. Booker’s current supporters and rally new ones.

“What would you say to someone new to politics?” an audience member asked Mr. Curry on Friday, before he and Mr. Booker departed to celebrate the film at a party in Greenwich Village.

His answer reflected all he had learned from Mr. Booker. “Politics is rough and ugly,” the filmmaker said, “but we need people who are willing to go in and get pummeled, and go out and breathe, and go right back in.”