SACRAMENTO, Calif. (AP) — California Gov. Jerry Brown late Sunday vetoed legislation that would have forced presidential candidates to publicly share their tax returns in order to appear on the state's ballot.

The bill was aimed at forcing President Donald Trump to release his tax returns if he runs for the White House again in 2020 and to ensure that future candidates will reveal theirs. Trump bucked tradition and did not during his 2016 campaign.

The Democratic governor's action dashed the hopes of bill supporters who hoped California would move forward with the requirements even as similar measures failed in more than two dozen other states.

Brown said in a letter to lawmakers that he worried the proposed law might not be constitutional and that it could have led to other litmus tests for candidates.

"Today we require tax returns, but what would be next?" Brown wrote. "Five years of health records? A certified birth certificate? High school report cards? And will these requirements vary depending on which political party is in power?"

Tax returns reveal income sources, charitable giving, exemptions and other financial information.

Trump said he did not want to disrupt an ongoing federal audit of his returns by releasing his. But his opponents and critics argued they would have shown conflicts of interest or that Trump paid little to no federal income tax.

For decades, every major party presidential candidate — except Trump — has released his or her tax returns.

Opponents of the disclosure bill questioned whether it was constitutional, arguing the U.S. Constitution already outlines the qualifications to be president. Democratic office holders, though, have argued that states have the power to determine ballot access.