Rep. Dan Crenshaw, R-Texas, has a congressional office in Washington, D.C., but he remains ever a Navy SEAL. The 35-year-old refuses to sit down when he arrives for our interview. “We’re too exposed,” Crenshaw tells me as he approaches the outdoor table I’ve chosen for our interview. It’s a Houston breakfast spot called Snooze. He points to a table on the perimeter covered in pollen. “Let’s sit there.” We sit in bright orange chairs, and now, from his vantage point, Crenshaw can see the entire outdoor patio, the adjacent patio, and the street. He instantly relaxes, orders a double shot mocha with a little less chocolate and the “Smashed Avocado Benny,” and answers questions on a variety of topics, including President Trump, immigration, national security, his military service, his beer preferences, and “Saturday Night Live” star Pete Davidson. If Trump and Rep. Alexandria Ocasio-Cortez, D-N.Y., represent the polar opposites of our social media-driven political culture, then Crenshaw might be the man in the middle: an antidote to chaos in an ever-changing Washington, D.C. He is at once a former SEAL still on a mission to cure what ails this country with his Harvard intellect, special operations forces-grit, and “Texas Forever” sensibilities. Everything Crenshaw does — from his social media posts to his border control policy proposals, and even where he positions himself in an interview — is resolute, methodical, and deliberate. This is most obvious...