The next most liberal bloc of voters on the spectrum are those who back civil unions rather than SSM, but they don’t like SSM bans much either. They tend to be about 7-8% of the electorate. This is the bloc whose votes are going to decide passage or nonpassage of this ban in California. I think it’s fair to assume they lean against banning SSM.

The ban side is pretty much assured of a baseline of 46% or 47%. I don’t know whether they’ll even try to really appeal to undecideds. It’s frankly easier and cheaper for them to try to win on upping turnout of people they have or can easily convince their way- religious adherents and old people.

The way to spoil that is to send people into their churches to politely but firmly advocate against the ban, to firm up the liberals and moderates among the churchgoers. Who tend to get talked into voting reactionary simply because no one shows up and says “that is wrong, and you’re doing wrong to real people”.