Anecdotal evidence
In Stillwater, there are a ton of lawn signs for mayoral and sherrif candidates. But until this past weekend, I had not seen any for the Sixth District race. I drove around Stillwater a fair amount over the past few days. Here are my sign counts:
Patty Wetterling: 3
Michele Bachmann: 1 (this was not even in Stillwater, it was on 36 on the right side as you're heading east, about 4-5 miles outside of town.)
John Binkowski: 0
Significant? Probably not. But even on her home turf, Michele Bachmann does not appear to be enthusiastically supported by her constituents.