WASHINGTON – The Empire strikes back? First, the Republican Party made Donald Trump sign an oath of loyalty by pledging to support its eventual presidential nominee and not run as a third-party candidate. Now, the establishment GOP may be planning to do the very thing it made Trump promise not to do: bolt from the Republican party and run a third-party campaign. Mark McKinnon, former President George W. Bush’s chief media strategist, suggested a scenario to NPR the GOP elite might follow if it looks like Trump will win the party’s presidential nomination. “The Republican establishment completely freaks out. They...