Presidential challengers hoping to glide to victory through California’s newly relevant primary, a heads-up: Your electoral fate may hinge on convincing enough left-leaning millennials to send postcards over the holiday season.
Welcome to the quirk-filled world of California election law. Here, voters without a registered political party can participate in the Democratic Party’s “open” presidential primary—but only if they ask for the right ballot.
Those who vote the old-fashioned way, in person at the polls, can simply request their presidential ballot of choice on the spot. But for those who vote by mail (now a majority of the state’s electorate), that request takes a remarkably analog form: a postcard signed and sent to the county registrar of voters.
If voters skip that step, the section of their ballot reserved for presidential candidates will be blank.
“Very few independent voters know that they have to do something to get the presidential ballot,” said Paul Mitchell of Political Data Inc., which analyzes electoral data for campaigns. He predicts the status quo could disenfranchise a million would-be presidential voters in California.

