California Democratic Gov. Gavin Newsom signed a bill Tuesday that will require presidential candidates to disclose the last five years of their taxes in order to appear on the state primary ballot, the latest Democratic-led state to pressure President Donald Trump to reveal his financial information or risk being kept off the ballot.

The Presidential Tax Transparency and Accountability Act requires a candidate for president or California governor to file copies of their Internal Revenue Service filings for the most recent five years at least 98 days ahead of the primary election.

California’s move is another step in the battle to force Trump to disclose his taxes, and the President’s attorney quickly threatened to challenge the new law in court.

In 2016, Trump bucked tradition by refusing to voluntarily release his tax returns, prompting questions and lawsuits about potential conflicts of interest. Several Democratic 2020 candidates have already released their tax information, seeking to draw a contrast with Trump. —CNN