The Milwaukee suburbs are moving sharply to the left—and that's a huge problem for Republicans

In few places has the flight of suburban voters from the Republican Party during the era of Donald Trump been as vividly showcased as in the three counties that surround Milwaukee—an exodus that reached new heights on Tuesday night when progressive Judge Janet Protasiewicz achieved a resounding victory in her quest to join the Wisconsin Supreme Court.

Those populous counties—Waukesha, Ozaukee, and Washington—are so well-known as the top bastion of GOP support in the state that they even have a collective nickname, the "WOW" counties, that signifies their strong tendency to vote together. For generations, the WOW counties were crucial building blocks for any Republican hoping to win statewide: Since the height of the New Deal, they supported a Democrat for president just once (Lyndon Johnson, during his 1964 landslide) and often gave GOP candidates margins of 30% or more. And high levels of voter participation, thanks to relatively high levels of income and education, allowed them to punch above their weight statewide.