The Constitution doesn't cover Presidential elections. It only requires that the state legislatures select a slate of electors to the Electoral College, by whatever means the state chooses. Holding an election is only one possible way. It isn't required. The states have carte blanche to decide how they pick electors. I see nothing unconstitutional about this bill.
It should be obvious however that Trump could refuse to comply and be omitted from the California ballot, and it would have no effect on his ability to win. He is never going to get the California electors anyway.
The Constitution spells out eligibility for office of POTUS and it says nothing about “must release tax returns”.
The states have carte blanche to decide how they pick electors. I see nothing unconstitutional about this bill.
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So California, and all the states with Democrat legislatures as soon as they assumed power, could decide that their electors would always go to the Democrats, even if their voters wanted to change their minds, effectively precluding us from ever having a Republican president? That’s not what our founding fathers intended, even though the Democrats, developing a sudden yen for language literalism, could argue to the contrary.