Democratic presidential front-runner Hillary Clinton Hillary Diane Rodham ClintonJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Momentum growing among Republicans for Supreme Court vote before Election Day Warning signs flash for Lindsey Graham in South Carolina MORE has a 13-point lead over rival Bernie Sanders Bernie SandersNYT editorial board remembers Ginsburg: She 'will forever have two legacies' Two GOP governors urge Republicans to hold off on Supreme Court nominee Sanders knocks McConnell: He's going against Ginsburg's 'dying wishes' MORE in California, according to a new Hoover Institution Golden State poll.

Clinton has 51 percent support among likely Democratic primary voters to 38 percent for Sanders.

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Sanders has the edge among younger voters. He got 61 percent of voters under 30 years old in the poll, to 30 percent for Clinton.

And among voters with "no party preference," Sanders leads by 40 points.

In a possible general election match-up, Clinton leads presumptive GOP presidential nominee Donald Trump Donald John TrumpUS reimposes UN sanctions on Iran amid increasing tensions Jeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Trump supporters chant 'Fill that seat' at North Carolina rally MORE 45 percent to 33 percent, with Libertarian candidate Gary Johnson Gary Earl JohnsonWhat the numbers say about Trump's chances at reelection Presidential race tightens in Minnesota as Trump plows resources into state The Hill's Campaign Report: Biden condemns violence, blames Trump for fomenting it l Bitter Mass. primaries reach the end l Super PAC spending set to explode MORE taking 4 percent.

The survey was conducted among 1,700 Californians May 4–16. The margin of error is 3.47 percentage points.

According to the RealClearPolitics average of polls, Clinton has an 8-point lead over Sanders in California.

But one recent poll showed her with just a 2-point lead in the Golden State.

Clinton is expected to add more campaign stops in California ahead of the primary next week.

Sanders has said he plans to remain in the race until the Democratic National Convention in July and will fight for every delegate possible. He said he expects to do well in delegate-rich California and has vowed to stay in despite Clinton's delegate lead.