Inside Kevin de León’s quest to topple Dianne Feinstein, the queen of California

CLAREMONT, CALIFORNIA — Kevin de León is cool in that way your dad is cool, which is to say he’d be insanely cool for the United States Senate. This particular Sunday, he’s sporting bright white Adidas sneakers, which are somehow scuffless even after the morning’s Central American independence parade. He’s wearing jeans; he left his tie at home.

De León is running late, but the 40 or so people gathered at a Persian restaurant in Claremont, California, are unbothered. When he ...