California Democrats have declined to endorse Sen. Dianne Feinstein’s bid for re-election in 2018, rebuking a powerful senator the party’s activist base sees as too conservative for the famously liberal state.

Instead, the state party’s executive committee voted late Saturday to endorse her challenger, state Sen. Kevin de Leon, in the general election. Currently the 51-year-old leader of the state senate, De Leon is held in high esteem by the party’s far left as the principal author of SB54, California’s controversial sanctuary state law.

De Leon won 65 percent of the 333 board members, easily clearing the 60 percent threshold needed for an endorsement. Another 28 backed a “no endorsement” option, while just 7 percent voted for Feinstein.

Prior to Saturday’s vote, Feinstein’s team had urged party delegates to support the “no endorsement” policy in a nod to party unity. Feinstein recruited Democratic heavyweights to plead her case, including Gov. Jerry Brown, Sen. Kamala Harris and two former state party chairmen. (RELATED: Obama Throws Support To Feinstein In Race Between Liberal And Centrist Dems)

The push was not enough to sway the executive committee, which has been moving away from Feinstein’s brand of center-left politics for years. Although the board represents a small fraction of a state party with about 7.4 million registered voters, its endorsement of de Leon could pave the way for a power shift away from establishment Democrats toward a new generation of progressive leaders.

“The nation’s most accomplished Democratic Party is leading the call for a new generation of leadership who will fight to advance a bold agenda,” de Leon said in a statement. “We have presented Californians with the first real alternative to the worn-out Washington playbook in a quarter-century.”

Even with the party’s endorsement, de Leon still faces an uphill climb to unseat Feinstein, who has represented California in the Senate since 1992. In the state’s all party primary in June, Feinstein crushed de Leon by 32 percentage points and garnered better than 70 percent of the total Democratic vote. Feinstein also holds a massive fundraising edge — she reported $10.3 million cash on hand at the end of March, compared to about $672,000 for de Leon, reports POLITICO.

Still, de Leon’s victory in the executive committee is likely to boost his campagin and draw a fresh round of donations from California’s left-wing base. De Leon also counts among his allies several influential Californians, including billionaire Democratic activist Tom Steyer.

“I think it’s always good to have younger generations rise up and assume positions of leadership,’’ de Leon told POLITICO Saturday. The vote was not about gender or age, but “about the right values,” he added.

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