Donald Trump has officially sunk 'disloyal' Texas Senator John Cornyn, but his high-stakes gambit to oust a veteran Republican will almost certainly cost the party. Top Republicans think the Texas tab could top $200 million. The worst-case cost for the GOP? The prized red state Senate seat falling into Democratic hands in six months. Cornyn's resounding double-digit defeat to Texas Attorney General Ken Paxton in Tuesday evening's runoff demonstrates Trump's enduring stranglehold on the GOP. But his decision to punish a well-funded incumbent and instead throw his weight behind a scandal-plagued nominee now presents fresh problems for the party. The...