Rep. Mary Fallin handily won Oklahoma’s GOP gubernatorial primary Tuesday, while former state Rep. Kevin Calvey and youth camp director James Lankford are headed to a runoff in the race to succeed her in the Oklahoma City-based 5th district.

Lankford was at 33.6 percent while Calvey was at 32.5 percent, with 99 percent of the vote counted. Because no candidate crossed the 50 percent threshold, the GOP nominee will be decided in an Aug. 24 runoff. Calvey has the support of the conservative, anti-tax Club for Growth, while Lankford has some support from tea party conservatives.

State Reps. Mike Thompson and Shane Jett and urologist Johnny Roy were among the candidates who trailed Calvey and Lankford and failed to make the runoff.

The winner of next month’s Republican contest will be the prohibitive favorite against Democrat Billy Coyle in November. Coyle, a lawyer, defeated retired professor Tom Guild in Tuesday’s primary. In 2008, Sen. John McCain (R) carried the district with 59 percent of the vote, and Democrats are not contesting the open-seat race in the conservative district this fall.

Elsewhere in the Sooner State, Republican Reps. Tom Cole and John Sullivan easily dispatched primary challengers, each ending the night well over the 50 percent needed to avoid a runoff. The only Democratic member of Oklahoma’s delegation, Rep. Dan Boren, defeated challenger Jim Wilson with 75 percent of the vote.

Sen. Tom Coburn, who is up for re-election this fall, sailed to victory over two little-known Republicans. Neither the Senate race nor the state’s five Congressional races are expected to be competitive in November.

Meanwhile, Fallin handily won the GOP nomination in the state’s open-seat gubernatorial race Tuesday night. She received 57 percent of the vote to avoid a runoff over two other candidates. Fallin was the state’s first female lieutenant governor and was elected to Congress in 2006.

She will begin the general election contest as the favorite over either state Attorney General Drew Edmondson or Lt. Gov. Jari Askins. Askins was ahead in the Democratic primary 51 percent to 49 percent with 83 percent of precincts reporting.