Oklahoma voters headed to the polls Tuesday to narrow the field in several statewide races, including open contests for governor and U.S. Senate. Candidates who failed to receive more than 50 percent of the vote advanced to Aug. 25 runoff elections.

In the race to succeed term-limited Gov. Kevin Stitt, Attorney General Gentner Drummond and former State Senator Mike Mazzei emerged as the top two finishers in a crowded nine-candidate Republican field and will meet in a runoff. State Rep. Cyndi Munson won the Democratic nomination outright and advances to the November general election.

For Oklahoma's open U.S. Senate seat, Republican Congressman Kevin Hern secured his party's nomination by winning a majority of the vote and avoiding a runoff. On the Democratic side, N'Kiyla Thomas and Jim Priest advanced to an August runoff after neither candidate reached the 50 percent threshold.

In the lieutenant governor's race, Republican T.W. Shannon won his party's nomination outright and advances to the November election, where he will face Democrat Kelly Forbes.

Republican Jon Echols secured his party's nomination for attorney general and will face Democrat Nick Coffey in November.

In the race for state auditor and inspector, incumbent Republican Cindy Byrd won more than 60 percent of the vote to earn another term on the November ballot. She will face Libertarian Kiefer Perry. No Democrat filed for the office.

The race for state superintendent of public instruction will be decided in an Aug. 25 Republican runoff between Robert Franklin and James Taylor. On the Democratic side, pastor and former Tulsa school board member Jennettie Marshall won her party's nomination and will advance to the general election.

For labor commissioner, State Reps. Kevin West of Moore and John Pfeiffer of Orlando advanced to a Republican runoff. The winner will face Democrat Kevin Dawson and Libertarian Mike Hall in November.

The Republican primary for insurance commissioner also heads to a runoff, with former State Sen. Marty Quinn of Claremore and Tulsa insurance professional Bob Sullivan advancing. Democrat Craig McIntyre is unopposed and will appear on the November ballot.

For the Oklahoma Corporation Commission, Republican Brad Boles of Marlow and Democrat Rhonda Eastman won their respective primaries and will face each other in the general election.