Secretary of State Alison Lundergan Grimes says the low turnout forecast is based on about 5,100 absentee votes cast and results from previous elections.
Attorney General Jack Conway is likely to win the Democratic primary for governor.
Republicans Matt Bevin, James Comer, Hal Heiner and Will T. Scott are all vying for the Republican nomination. Incumbent Democratic Gov. Steve Beshear cannot seek re-election because of term limits.
The Republican primary for governor has been contentious. Grimes said negative campaigning usually depresses turnout, citing