Friday is the first of Oklahoma's three-day early voting period at county election board offices across the state.
Voters can cast their ballot from 8 a.m. to 6 p.m. Friday and Monday and 8 a.m. to 1 p.m. on Saturday.
State officials say turnout for this year's primary election is expected to be light, with only one statewide race on the ballot where two Republicans who are running for a six-year term on the Oklahoma Corporation Commission.
State Election Board Secretary Paul Ziriax says there could be pockets of relatively heavy turnout, especially in the 2nd Congressional District in eastern Oklahoma, where there are both Democratic and Republican primaries.
A reminder, voters will need to bring their voter registration card with them to their county election board office.
The Associated Press contributed to this story.