LANSING, Mich. (AP) — Michigan is among five states where Republicans retained control of the state House even though Democratic candidates won more votes statewide last fall, according to an Associated Press analysis.
The House districts showed the fourth-highest GOP advantage among all states, trailing Wisconsin, South Dakota and Florida. The AP used a statistical method of calculating partisan tilt, the so-called "efficiency gap," that is designed to flag cases of potential political gerrymandering.
The examination also revealed that while Democrats flipped two Michigan congressional seats in 2018, it could have been three if not for the structural advantage enjoyed by Republicans, who drew the state legislative and congressional maps following the 2010 census.
Democrats had a good 2018, winning the governor's race and all other statewide offices while making gains in the Legislature, which remains under GOP control. But the efficiency gap analysis, which assumes that a party increases its seat share by 2 percentage points for each 1 percentage point gain in its statewide vote share, showed that Republicans won nearly 12 more state House districts than would have been expected based on their portion of the vote — more than enough to keep the majority.
GOP candidates received 46 percent of the two-party vote compared to Democrats' 54 percent, yet the GOP won a 58-52 seat advantage over Democrats.
The efficiency gap grew for the state House map from 2016 to 2018 and narrowed for the congressional seats.
The formula does not necessarily prove political shenanigans, because partisan advantages also can arise naturally based on where Democratic and Republican voters choose to live.
But Michigan Democrats have pointed to efficiency gaps in a lawsuit challenging the constitutionality of the congressional and legislative maps, which they contend are the most pro-Republican partisan gerrymanders in modern state history. A federal court panel held a trial in February and has not yet ruled.
Republicans who intervened in the case argued that using the efficiency gap to demonstrate how voters are packed into or spread among certain districts is deficient because the test depicts harm on political parties, not individual voters. They also say the statistical method shows only averages, not specific harm.
The plaintiffs, including the League of Women Voters and 11 Democrats, said it is clear the Legislature discriminated against individual Democratic voters by minimizing or preventing Democrats from being elected.
The lawsuit only pertains to the 2020 elections.
In November, Michigan voters approved a constitutional amendment creating an independent commission to handle the typically once-a-decade redistricting process after the 2020 census, taking that duty away from the Legislature and governor.
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