pits newsom in another and more personal fight with trump, as california dives into the trump tax battle. federal government is not able for tors his hand, california will. reporter: state senator mike mcgwire introduced the bill and saying it s all about presidential transparency. if you re a democrat or a republican, you can choose not to release your tax forms, but you simply won t be on the california ballot. reporter: there s one person who vehemently resisted releasing his tax returns. we all know that s hog wash. reporter: four years trump has refused to budge. i would love to give them, but i m not going to do it. it s very simple. reporter: to force trump hand s states are jumping in. this year, states introduced similar bills, california is expected to face legal challenges but democrats say they re not worried. this bill applies to all
he doesn t, it could cost him to lose millions of votes in 2020. mr. secretary, call the roll. reporter: gauntlet thrown in the latest battle for president trump s taxes. california governor gavin newsom signed a bill to require presidential and gubernatorial candidates to release their tax returns in order to qualify for the state s 2020 primary ballot. you have a right as an american citizen to know what is going on. you have a right to know if someone is self dealing. reporter: the latest move pits him in another and more personal fight with trump. as california dives into the trump tax battle. the federal government is not going to be able to force his hand, california will. reporter: state senator mike mcguire introduced the bill and said it is all about presidential transparency. if your a democrat or a republican, you can choose not to release your tax returns. you simply won t be on the california ballot. but there is only one person who hat vehemently resisted