Left-wing Democrats launched their first major attacks this weekend against former vice president Joe Biden, who is currently the frontrunner in the race for the Democratic Party’s presidential nomination in 2020.

The Washington Post reported that many of the 14 candidates — out of a total of 23 — who appeared at the California Democratic Party convention in San Francisco this weekend took veiled — and not-so-veiled — shots at Biden, who chose not to attend:

The liberal wing of the Democratic Party launched a sudden volley of attacks against presidential candidate Joe Biden and his allies over the weekend, showing a new urgency to wrest control of the party from moderate forces that had seized an advantage in recent months.

Some of the most scathing, if veiled, admonitions came Sunday from Sen. Bernie Sanders (I-Vt.), who repeatedly condemned “middle ground” policy ideas and appeared to criticize Biden for not attending a Democratic gathering where Sanders and 13 other White House hopefuls spoke.

“We cannot go back to the old ways,” Sanders warned in a speech at the California Democratic Party convention here as supporters cheered and waved signs bearing his name. “We have got to go forward with a new and progressive agenda.”

In Biden’s absence, the San Francisco Chronicle noted, other candidates had a chance to shine — including Sen. Elizabeth Warren (D-MA), who has struggled thanks to controversy over her past claims to Native American heritage, but whose “policy-for-everything” approach has won her renewed support and respect from the party’s liberal base.

The Chronicle noted:

Many around the Moscone Center said Warren belonged with [California Senator Kamala] Harris, Vermont Sen. Bernie Sanders and former Vice President Joe Biden as the early leaders vying for California’s nearly 500 delegates to the party’s national convention.

“She had a crisp, energetic message with a clear enemy: billionaires and corporations,” said California Democratic strategist Rose Kapolczynski, who is not affiliated with any campaigns. “And, as she likes to say, she has a plan for how to change things.”

“I was totally shocked by Elizabeth Warren,” said Democratic Assemblywoman Lorena Gonzalez of San Diego, who has not endorsed a candidate. “She was on fire here. It was incredible.”

Others have attacked Biden in the past few weeks — notably Rep. Alexandria Ocasio-Cortez (D-NY), who blasted Biden’s call for a “middle ground” approach to climate change a “dealbreaker.” Sanders has also criticized Biden — as he criticized Hillary Clinton in 2016 — for voting for the Iraq War.

California has moved its primary from June to March, when it will join the large number of states that vote on “Super Tuesday,” the fifth contest of the primary campaign. As a result, the state could play a decisive role in the contest.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He is a winner of the 2018 Robert Novak Journalism Alumni Fellowship. He is also the co-author of How Trump Won: The Inside Story of a Revolution, which is available from Regnery. Follow him on Twitter at @joelpollak.