How Kevin McCarthy’s political machine worked to sway the GOP field

Rep. Madison Cawthorn (R-N.C.) made a name for himself as a firebrand social media phenomenon who delighted in trolling the left, famously boasting to colleagues that he had built his House office by focusing on communications not legislation.

But the strategy made him vulnerable to forces within his own party that helped end his time in office. Top allies of Kevin McCarthy, the House Republican leader, worked this spring to deny Cawthorn a second term in office, after the Donald Trump-endorsed lawmaker made controversial comments about cocaine use and sex...