I'm not sure how many measures that restrict equal treatment of gay couples will be voted on this year. Proposition 8 in California and Proposition 102 in Arizona are two of them. They ask voters to limit the right to marry to straight couples. Here is the full text of each:
Prop. 8: Only marriage between a man and a woman is valid or recognized in California. link.
Prop. 102: Only a union of one man and one woman shall be valid or recognized as marriage in this state. link.
I think these amendments violate the Equal Protection Clause of the United States Constitution. Jim can marry Julie, but Jane cannot. The only reason Jane cannot is that Jane is a woman. Thus, these laws discriminate based solely on gender. Gender is a protected class.
That said, I think it would be much better to win these initiative fights, and to win them by convincing the population at large that it is the right thing to do. Basically, I think justice minded Christians need to first show others that the Bible does not mandate unequal treatment of gays. Then we must show others that the central message of Jesus Christ demands equal treatment of all of God's people.