Rep. Jim BridenstineJames (Jim) Frederick BridenstineOvernight Energy: Dems go on attack at EPA chief's hearing | Pruitt backs national fuel standard | Bill Nye sparks controversy with State of the Union plans | Greens sue over wolf protections Bill Nye's company says SOTU attendance not an endorsement Scientists' group rips Bill Nye over SOTU attendance: He 'does not speak for us' MORE (R-Okla.) will not run for Senate in Oklahoma, multiple sources confirmed to The Hill.

Bridenstine spent part of the afternoon on Tuesday calling around to supporters to let them know he’s decided against running, including former Kansas GOP Rep. Jim Ryun, who heads the conservative group Madison Project, which had encouraged him to run.

His decision comes shortly after The Hill reported Tuesday morning that Oklahoma House Speaker T.W. Shannon will launch his own campaign for retiring Sen. Tom Coburn’s (R-Okla.) seat on Wednesday.

Bridenstine and Shannon were expected to compete for the same universe of conservative voters, if both entered the Republican primary.

National conservative groups had been urging Bridenstine into the race, with the Senate Conservatives Fund lauding him as a strong potential Senate candidate in their endorsement of him last year.

Though he would’ve had considerable support from those groups in the race, Bridenstine was expected to face fundraising difficulties within Oklahoma. That, coupled with his short tenure in Washington, sparked skepticism about his chances among politicos in Oklahoma and D.C.

Republicans now face a primary contest between Shannon and Rep. James Lankford (R-Okla.), who jumped in the race last week to heavy criticism from conservative groups.

It's likely that the national conservative groups who were encouraging Bridenstine to run will remain neutral in the race.