President Trump blistered Representative Elijah Cummings on Twitter, calling out the chairman of the House Oversight committee for raising the hue and cry over conditions on the Mexican border, “when actually his Baltimore district is FAR WORSE and more dangerous. His district is considered the Worst in the USA.” Trump went on to describe Cummings’s West Baltimore constituency as “a disgusting, rat and rodent infested mess. If he spent more time in Baltimore, maybe he could help clean up this very dangerous & filthy place.” Predictably, the Left—including most of cable news—rushed to condemn Trump as a racist. Speaker Nancy...