President Trump’s campaign and the Republican party are suing the state of California over a law requiring all presidential candidates to turn over their tax returns to appear on the state’s primary ballot, the Associated Press reports. The legislation, which has been described in one GOP lawsuit as “a naked political attack against the sitting President of the United States,” was signed last week by Democratic Gov. Gavin Newsom. Since then, two lawsuits have been filed in U.S. District Court in Sacramento. The law requires presidential and gubernatorial candidates to release five years of tax returns in order to qualify for the primary, but the requirement does not apply to the general election. Trump has famously refused to release his returns, and his counsel Jay Sekulow said the legislation is “flagrantly illegal.” The lawsuits allege the law violates the Constitution by violating citizens’ rights to choose a candidate.