The candidates are competing for the right to represent the 2nd District, which includes 25 eastern and southeastern Oklahoma counties.
The competition is being closely watched nationally as Republicans view it as an opportunity to potentially pick up a seat in a district that is overwhelmingly Democratic in voter registration but composed primarily of rural conservatives.
Democrats have expressed optimism that they will be able to retain the seat.
Boren, of Muskogee, is currently the lone Democrat in Oklahoma's congressional delegation.
He is retiring from the position.See All Results of the Aug. 28 Runoff Election