Former Minnesota Gov. Arne Carlson (R) is endorsing
Usually when you hear these sorts of stories it's someone who was governor for like one term in the 1970s or something, when party divisions were very different from today. Carlson, though, was Minnesota Governor for most of the 1990s. My recollection is that he basically got run out by the hard right faction of the GOP in the state. But he was a moderate, but a genuine Republican. He cited Bachmann's tirade as one thing that pushed him to endorse.