What the powers that be fear and loathe more than anything else is loss of control. Lil' Donnie Trump has deviated from the script and in so doing has caused a firestorm of angst over the possibility that he just might force the Republicans to make him their nominee for president by their own rules and nominating process.
That's what all this sturm und drang (storm and stress--turmoil) over Lil' Donnie's candidacy is all about. As politically incorrect as it is think so, there are enough angry white men (and women!) among Republicans to give the nomination to Lil Donnie. Since Lil' Donnie has virtually no coat tails nationally to enable the party regulars to maintain the indulgent lifestyle to which they have grown accustomed, there is existential panic in their ranks.
The Hillary was supposed to be destined to win the White House as yet another potent symbol candidate (first African-American, followed by the first woman, followed by ??? etc), but so long as Paul and Mitch controlled the house and Senate so what? "Obstructionism is us" has been the GOP slogan for the past 8 years, it could continue for another 8 years, unless...all those angry white men and women for Trump decide to either stay at home or vote for the opposition just to get rid of the same old crowd in DC.
After former speaker John Boehner (how is that last name pronounced again?!!) described Ted Cruz as "Satan incarnate", that just leaves Governor Beige Bland (otherwise known as John Kaisich) unless...the cry goes out for JEB! as the compromise candidate that even Boehner could like--now that's a loser who would not threaten the regular party apparatus. The odds of such happening are a million to one, but then so was Bernie Sanders' candidacy)