All 38 seats in the Michigan Senate are up for election in 2014. Republicans currently have a 27-11 supermajority, and have controlled the senate since 1983. Republican control of the state senate has prevented democrats from complete control of Michigan’s government in some years, and stopped a lot of bad things from being passed.
Fortunately for Republicans, the Michigan state senate is up only in midterms, which usually favor Republicans much more than presidential years. Republicans had a good year in 2014, picking up one state senate seat, following four pickups in 2010.
The 2010 redistricting produced a map that was moderately pro-Republican, while complying with all relevant laws.
There are 26 open seats due to term-limits, 7 D and 19 R. There may be other openings due to retirement or seeking another office.
All current state senators are former state representatives except three (Colbeck, Conyers, Hertel). This pattern held in the past, and most credible candidates this time are current or former state reps.
I have included election data for the 2014 state senate election, and McCain (2008), Romney (2012), and Trump (2016) results in each district. More data is available from Republican Michigander and RRH Elections.
The McCain numbers look terrible for Republicans because he collapsed after publicly pulling out of Michigan. The largest McCain percentage in any Michigan state senate district won by a democrat in the past twelve years is 46.2% in (old) district 31.
Here is a breakdown of the individual races. State reps years in office are listed after their names, with P meaning present.