Nearly 150,000 voters have had their mail-in ballots rejected for California’s June primary election, a sharp spike from previous primaries. According to state data, 148,241 mail ballots were rejected in the June election, or a rate of 1.73%. That’s up from the previous two primaries. Kim Alexander, president of the nonpartisan California Voter Foundation, says postmarks applied too late are the main driver of mail ballot rejections. In January, a group of mostly Democratic U.S. senators sent a letter to the U.S. Postal Service, alarmed that mail-processing changes might affect postmark dates.