Even the most competitive and evenly balanced states are infected by the same contagion as the hardened one-party states.

The North Carolina Republican had already made up his mind to leave the Senate, but the run-in with the president over Medicaid moved up the timeline of the announcement.

Flake. Corker. Romney. And now, Sen. Thom Tillis. The roll call of Republican senators in the U.S. Congress who have called it quits, rather than endure a political career sideways with President Donald Trump,