An Arizona nonprofit made the contribution to defeat Proposition 30 and support Proposition 32 on last month's ballot.
The money had been funneled through three other nonprofits allowing donors to remain anonymous.
Democratic Assembly member Roger Dickinson says he's proposing a bill that would require donor disclosure of any contribution of $50,000 dollars or more from a multipurpose organization to a campaign.
Dickinson: "I think this legislation will take a big step in the direction of making sure that public has what they need to know to make the best decisions possible on issues of public importance."
Democratic Senators Mark Leno and Jerry Hill are also introducing bills that would require clear identification of the top three funders of political ads, both in the ads themselves and on the campaign's website.