Beto O’Rourke is running to replace Ted Cruz. Literally. Sweat pours off his lean, 6’ 4”-frame as the El Paso Democrat jogs along the southern bank of the Trinity River surrounded by 300-odd supporters and curious voters jogging along with him. Incredibly, they have shown up at 8 a.m. on a Sunday to join him for a double shot of politics and cardio. In between panting breaths, O’Rourke explains to me the origins of this novel campaign event, which has him running several miles under the Texas sun, stopping in the middle to take questions and lingering at the end...