SAN FRANCISCO (Reuters) - (This June 1 story has been corrected to remove reference in paragraphs 12, 14-15 to a pamphlet purporting to be from the campaign of former Vice President Joe Biden, criticizing Bernie Sanders. It was not from Biden. Corrects spelling of Senator Booker’s name in fifth paragraph.)

Fourteen Democratic presidential candidates sparked cheers and applause in the streets of San Francisco on Saturday as they worked the crowds at the California party’s state convention, a sign of the state’s heft in upcoming nominating contests.

Their presence lent star power to a state organizing convention that has become a window into the issues and rivalries at stake as Democrats compete for the nomination to run against Republican President Donald Trump in 2020.

“Oh my God, is that Bernie Sanders?” a young woman yelled as she walked past the tousle-haired progressive icon, who was taking selfies with admirers after addressing a union group.

Following an evening of parties including one emceed by a drag performer in the LGBTQ-friendly city, presidential hopefuls including Sanders and fellow U.S. Senators Kamala Harris and Amy Klobuchar addressed members of the Service Employees International Union before heading into the main convention hall.

“This election is not about one guy in one office,” New Jersey U.S. Senator Cory Booker exhorted the crowd in an afternoon speech. “It is about a referendum on who we are and what me must be to each other.”

Harris, who has been eclipsed in early polling in California by former Vice President Joe Biden and Sanders, made clear she was not taking her home state for granted.

Supporters with signs bearing her name and shouting “Kamala! Kamala!” formed a gauntlet outside of the SEIU event that Sanders was forced to walk through.

“I am here to earn everyone’s support, and I’m going to fight to earn it,” she said at a breakfast held by the party’s women’s caucus.

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Despite Harris’ clear organizational clout, however, it was U.S. Senator Elizabeth Warren who drew the greatest cheers from the progressive crowd on Saturday, far more than Harris or former Texas Congressman Beto O’Rourke.

To screams and whoops, Warren called for universal free preschool and childcare, forgiveness of student loan debt, free college and a wealth tax on the highest earners.

“That’s two cents on the dollar for people with fortunes worth more than $50 million,” Warren declared in an old-school political speaking style that swelled for emphasis as she reached each talking point. “They can afford two cents.”

Notably absent from the event was Biden. As the convention opened on Saturday morning, his aides moved among the crowd press area.

Biden leads in early polling in the state, but opted not to attend the convention, a move experts said could make him seem above the fray, but could also be risky if Californians come to see him as taking the state for granted.

In perhaps a sign of the campaign to come, Sanders, a self-described democratic socialist, polls second behind Biden among Democrats.

A moderate, Biden appeared to be staking a position to the right of Sanders.

Colorado Governor John Hickenlooper, who calls himself a pragmatic progressive, drew loud and prolonged boos when he told the crowd “Socialism is not the answer.” The boos drowned out Hickenlooper’s explanation that as a governor of a “purple” state with mixed Democrat and Republican voters, he was able to enact progressive policies by reaching out to opponents.

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It was not a welcome message at a convention where Sanders and Warren were greeted like rock stars. Other attendees emphasized their left-leaning positions, with Harris taking on Trump and demanding the House of Representatives begin impeachment proceedings against him.

“We need to begin impeachment proceedings and we need a new commander in chief,” she said.

When U.S. House of Representatives Speaker Nancy Pelosi, a Democrat who represents San Francisco, vowed to “investigate and litigate to protect our democracy,” yells of “impeach!” broke out in the convention hall. Pelosi has so far resisted Democratic calls to impeach Trump over actions many say were illegal, including possible obstruction of justice in the probe of Russian interference in the 2016 election that brought Trump to power.

Sanders is set to address the convention on Sunday. At the SEIU breakfast, he called the low federal minimum wage unacceptable and said it was a disgrace that millions of Americans did not have healthcare.

The convention opened with a moment of silence for the 12 victims of a gunman in Virginia Beach on Friday, the latest mass shooting in the nation.