This is really embarrassing.

JUST IN: Sanders supporters sue to extend California’s voter registration https://t.co/u6gVEEBZWY pic.twitter.com/TPaPPlDzvD

— The Hill (@thehill) May 22, 2016

“Mistakes are being made,” said William Simpich, an Oakland civil rights attorney who filed the lawsuit Friday, according to the Los Angeles Times.

The suit alleges that there is confusion over the rules for the presidential primary and requests that voter registration be extended until June 7. May 31 is the current deadline to request a ballot by mail.

In the state’s presidential primary, the parties control the contests. The Democratic primary has been opened up to voters who have “no party preference,” but the lawsuit says that isn’t being made clear to all voters.

“There’s mass confusion,” Simpich said in an interview on Saturday night with the Los Angeles Times. “This is a situation that really shouts out for some uniformity.”