Eric Swalwell before the fall. Photo: Demetrius Freeman/The Washington Post/Getty Images Until April 10, the general tenor of California’s contest to determine a successor to two-term governor Gavin Newsom had been low-key, even a bit sleepy. A large but far from star-studded field of eight Democrats and two Republicans had been slogging toward the June 3 nonpartisan top-two primary with no clear front-runner and all sorts of scenarios appearing possible, including a partisan “lockout” in which