Last week’s midterms were widely seen as a success for Wisconsin’s formerly near-powerless Democrats.
They unseated two-term incumbent Gov. Scott Walker, easily re-elected Tammy Baldwin to another term in the Senate and won a majority of the votes in a state that helped propel Republican President Donald Trump to victory just two years ago.
But despite winning over half of Wisconsin’s votes, they won just 35 of the 99 seats in the state Assembly.
“[Democrats] won all five of the statewide offices, something that has not happened in several decades,” UW-Madison professor and Elections Research Center Director Barry Burden said. “But their success came to a halt in the state legislature.”
Not a single incumbent Republican lost their spot in the Assembly, and Democrats only picked up one seat.
This did not result from a lack of trying; Democrats contested far more Assembly districts than Republicans, who did not run a candidate in 29 races, almost an entire third of the chamber’s seats.
Part of the explanation comes from the simple advantage of already holding office.
“One reason Republicans fared well is that they have more incumbents who are well known, well financed and fit their districts well,” Burden said. “It is always difficult for a challenger to defeat a sitting incumbent in elections where voters do not have a lot of information about the candidates.”
Largely, however, the answer lies in the maps.
In a process of self-clustering, Democrats tend to disproportionately live together in tightly packed cities, where their votes are “wasted,” as the political science literature puts it, in uncompetitive districts where they overwhelmingly elect Democratic representatives.
“In some districts, Democratic-leaning voters make 70 or 80 percent of the total,” Burden said. “Democrats have enough votes to win statewide elections when all votes are considered together but have difficulty when many of them are clustered in a small number of districts.”
But this already-existing Republican advantage has been exaggerated in recent years through the process of partisan redistricting, or gerrymandering.
With control of the governorship and state Legislature in 2010, Republicans drew district lines that entrenched and expanded the advantage brought on by this already existing systemic advantage.
“They built on the pre-existing benefit of having Republican supporters more evenly distributed around the state by creating maps to get even more seats than the mix of voters would be expected to produce,” Burden said. “Democratic victories were not a large enough wave to overcome the system of districts that have been in place for the last four election cycles.”
