Democrats Shouldn't Despair Over Gary Peters
His decision to retire made sense in several ways
There’s probably no great mystery as to why U.S. Sen. Gary Peters decided not to run for reelection two years from now, Democrats are unlikely to retake control of the Senate until 2029 at the earliest, and he would have been shut out of any real power until then, when he would be past 70.
He would have been a heavy favorite to be reelected, but would have had to raise tens of millions, and was neither a potential presidential candidate, nor did he seem to want to run for president.
I will have more on the anatomy of all this later, but here’s something to keep in mind: Republicans haven’t won a Senate election in Michigan since 1994, and that was the only time since 1972. With the inevitable midterm reaction against the Trump follies coming, Democrats — perhaps Pete Buttigieg — should be heavily favored to hold this seat.

I'd love to see Pete in the Senate!
Pete sounds like a great option, though it's early.