Many U.S. states have been considering proposals to introduce mandatory labeling requirements for foods containing GMOs. This paper analyzes precinct-level voting patterns in the case of California’s Proposition 37, which was narrowly defeated in the November 2012 ballot. Those voting patterns can be predicted primarily by support for Democrats, their platforms, and President Obama. Projections using our estimated model imply that a majority of voters in only three of fifty states (Hawaii, Rhode Island, and Vermont) plus the District of Columbia would have passed Proposition 37 had it been on their ballots in 2012.