Republican lawmakers are warily eyeing the possibility of a brokered convention that could force party leaders to choose between Sen. Ted Cruz (R-Texas) and celebrity businessman Donald Trump for their presidential nominee. It is, they say, a very difficult choice. From their perspective, it’s picking between the devil they know and the devil they don’t know. Many GOP senators have declined to state their preferences publicly while the race remains competitive. Privately, they are flummoxed at the possibility of likely having to choose between two candidates they view as highly problematic. Lawmakers who spoke to The Hill on background say...