When the recession looms, coexistence deteriorates. The obligation of the big parties is to reduce the tension and this happens, sometimes, by agreeing with the unruly in order to train them. It's the bear hug theory.
Kingmaker is used a lot in English, but Maker or Creator of Kings sounds weird in Spanish, although there were. Cardinal Cisneros was the successful creator of Charles V of Germany and I of Spain, and centuries later General Prim had less luck as a creator.