Michigan State Senate: The Senate did not hold elections in 2012.
Michigan House of Representatives: 18 incumbents retired in 2012, 9 Republicans and 9 Democrats. Republicans held a 63 to 47 majority, and the chamber was unlikely to switch control in 2012.
- District 4: Rose Mary Robinson beat out ten other challengers in the Democratic primary.
- District 40: Michael D. McCready narrowly won with only 32% of the vote, with runners-up David W. Potts and David Wolkinson each garnering 30%.
- District 76: Write-in candidate Winnie Brinks had to receive a minimum of 1000 votes in the primary on August 7 to get on the general election ballot in November, and she far surpassed that number, amassing more than 2,500.
- District 83: Republican incumbent Paul Muxlow escaped with a tight victory in one of the most anticipated races of the night, beating challenger Bob Eick 5,198 to 5,066.
- District 88: In an exceptionally close race for this open seat, Roger Victory defeated Amanda Sue Van Essen by 88 votes, among more than 12,000 cast in the district.
- District 107: In a race that has yet to be officially called, Suzanne Shumway (D) leads Jim Martin by 27 votes.
The following incumbents were defeated in the primary:
- Tim Bledsoe (D), District 2
- Jimmy Womack (D), District 3
- Maureen Stapleton (D), District 6
- Lesia Liss (D), District 28
- Kurt E. Damrow (R), District 84
- District 63: Democrat Bill Farmer took on Speaker of the House Jase Bolger (R), who was embroiled in a campaign rigging scandal. However, Farmer was defeated.
- District 76: Winnie Brinks (D) sought to capitalize on the same election rigging scheme that was embroiling Speaker Bolger, as she defeated Roy Schmidt (R) who defected to the Republican party just before the primary.
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