The California state Senate on Thursday approved a bill to require candidates appearing on the presidential primary ballot — including President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE — to release five years' worth of income tax returns.

The measure was approved in a 27-10 vote, according to The Associated Press. California, for the first time, will be one of the first states to hold its presidential primary in the 2020 cycle.

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The bill is a response to Trump's insistence that he will not release his tax returns as presidential candidates traditionally have done, claiming he is under audit. If the bill becomes law and Trump does not release his returns, he may not appear on the California primary ballot.

"We believe that President Trump, if he truly doesn’t have anything to hide, should step up and release his tax returns,” said state Sen. Mike McGuire (D) who co-authored the bill, according to the AP.

All 10 Republicans in the state Senate voted against the bill's passage.

“I get that playing the resistance card may be good politics for the majority party, but I would submit that it’s bad policy for Californians,” Sen. Brian Jones (R) told the wire service.

The state's legislature passed a similar bill in 2017, but then-Gov. Jerry Brown (D), who did not release his own tax returns, vetoed the bill. A spokesman for Gov. Gavin Newsom Gavin NewsomOVERNIGHT ENERGY: California seeks to sell only electric cars by 2035 | EPA threatens to close New York City office after Trump threats to 'anarchist' cities | House energy package sparks criticism from left and right California seeks to sell only electric cars by 2035 EPA head questions connection of climate change to natural disasters MORE (D) told the AP that if the bill was sent to Newsom's desk, "it would be evaluated on its own merits.”

Other presidential candidates would also be subject to the bill, but several 2020 Democrats have already released their tax returns.

Trump is facing one primary challenger, former Massachusetts Gov. Bill Weld William (Bill) WeldRalph Gants, chief justice of Massachusetts supreme court, dies at 65 The Hill's Campaign Report: Biden visits Kenosha | Trump's double-voting suggestion draws fire | Facebook clamps down on election ads Biden picks up endorsements from nearly 100 Republicans MORE (R).

Similar bills are making their way through the Washington and New Jersey state legislatures.