Where everything is bipartisan until it is not.
The do-over election held when no candidate achieves the required majority in the first round, forcing the top contenders into sudden-death overtime. It's democracy's version of "best two out of three," typically featuring just the top two vote-getters in a head-to-head showdown. Also the hydrological term for water that doesn't soak in, but the political usage is far more dramatic.