The most recent round of primary elections on May 19th presented a disappointing reality for opponents of the President. Donald Trump, despite falling approval ratings, once again proved the power of his endorsement within the bounds of his own party. Thomas Massie (R-KY), an incumbent Congressman, lost his re-election bid to a Trump-backed challenger, Ed Gallrein. Other candidates endorsed by Trump either won their primaries, like Andy Barr (R-KY), or advanced to runoffs, like Barry Moore (R-AL) and Burt Jones (R-GA). Gallrein’s victory over Massie was perhaps the most telling of these races because it illustrates not only an example of…