The Republican establishment is in a real tough spot. With Trump surging to a commanding delegate lead and Ted Cruz being the runner up, they have no where to turn. Their hand picked candidate Jeb, ran an abysmal campaign wasting over one hundred million dollars of donor funds for no victories. Their next option in Rubio was pummeled in his home state of Florida and dropped out. Their remaining candidate Governor Kasich only won his home state of Ohio and trails in the polls everywhere else.
Logically, the GOP establishment should be rallying to Ted Cruz, a verified conservative, in order to stop Trump. Since the establishment hates Cruz as well, they seem to be trying for a contested convention. However, this strategy is risky. If Trump or Cruz goes in with almost enough delegates for the nomination but then the establishment pulls the rug out and inserts their own candidate, the GOP convention would likely descend into open war.
The GOP ruling class is faced with three unpalatable ( to them) options: Trump as the nominee, Cruz as the nominee, or a brokered convention that would likely shatter the party. All of these choices promise trouble to the status quo.