SACRAMENTO, Calif. (AP) — Four California voters have sued to block a new state law aimed at forcing Republican President Donald Trump to release his personal income tax returns.

Democratic Gov. Gavin Newsom signed a law last week that requires presidential candidates to file five years of their income tax returns with the California Secretary of State at least 98 days prior to the primary election. Candidates who don’t do it won’t appear on the ballot.

Monday, the conservative group Judicial Watch announced it had filed a lawsuit on Thursday to challenge the law. It lists four California voters as plaintiffs, including two registered as Republicans, one registered as a Democrat and one registered as an independent.

The lawsuit alleges the law violates the First and 14th amendments to the U.S. Constitution.