Rep. Ro Khanna, a Democrat in his fifth term representing Silicon Valley, faces a new primary challenge from tech entrepreneur Ethan Agarwal. Benjamin Fanjoy/Getty Images Rep. Ro Khanna, who represents Silicon Valley, is facing a primary challenge backed by tech figures. It comes after Khanna publicly backed a wealth tax on billionaires. Here's what to know about the race. Rep. Ro Khanna endorsed a billionaire wealth tax. Now, he's facing a new tech-backed challenge to his reelection bid. E...