Supporters of Sen. Bernie Sanders are working to make California’s June primary as tough as possible for Hillary Clinton, with a federal lawsuit challenging the voter registration process in the delegate-heavy state.  

The odds are stacked high against Sanders wining the Democratic presidential nomination — it is mathematically impossible for him to win with pledged delegates, and Clinton leads among superdelegates, 525-39 . But the lawsuit filed Friday is just the latest sign that Sanders will not let up, forcing Clinton to devote resources to the primary battle right up to the end.  

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California is one of six states voting on June 7, with it and New Jersey representing the biggest prizes in terms of delegates.  

“You’re going to see me running all over California,” Sanders told ABC News  on Sunday. “We’re going to do everything that we can to get every vote and every delegate that we can and go into that convention with as much momentum as is possible.”  

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The lawsuit alleges widespread confusion over the state’s voter registration rules and asks for registration to be extended until the primary date, the Los Angeles Times reports . It also asks for a judge to make the state launch a public awareness campaign informing unaffiliated voters that they can vote in the state’s Democratic primary. Voters who call themselves independents have heavily supported Sanders .  

The plaintiffs include a group called the Voting Rights Defense Project, described as “an organization campaigning to heighten voter education and voter turnout for their candidate, Bernie Sanders,” the newspaper reported. Other plaintiffs include a local civil rights attorney and the American Independent Party, a minor party that is allowing unaffiliated voters to cast presidential ballots.  

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Clinton has insisted that the primary fight with Sanders is over and has tried to turn her attention to Trump, who is gaining on her — and even surpassing her — in some polls. But Sanders has launched an aggressive campaign in California, one of the last major primaries, with 475 pledged delegates at stake. Clinton won the state’s 2008 Democratic primary.  

Contact Akin at stephanieakin@rollcall.com and follow her on Twitter at @stephanieakin
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