That's a better showing for Land than she's had in previous polling: a recent survey from the Democratic firm Public Policy Polling found Peters up by 5 percentage points. Most observers believe Peters has the edge in the race, and some Republicans have been hoping Rep. Dave Camp (R-Mich.) decides to run for the seat. Camp said this week he's giving the race a more serious look than he has in the past.

Donne Research's track record isn't perfect — in 2012 they repeatedly found Mitt Romney running close to President Obama in the state, even though neither campaign treated the state as a competitive one and Obama carried it by 9 percentage points.

The poll of 600 likely voters was conducted on Jule 23 and 24 and had a margin of error of 4 percentage points.