Oklahoma’s search for a new coach is heating up, and several candidates have emerged as a likely contender for the job, according to two people familiar with the process.

Oklahoma athletic director Joe Castiglione said Wednesday he has spoken to a number of candidates for the position and that the search is ongoing.

Castiglionis team also has interviewed Oklahoma defensive coordinator Brent Venables for the role.

Venables, who previously coached at Iowa State and Oklahoma State, was named the Sooners’ head coach on Dec. 1.

OU hired Venables from Oklahoma State on Feb. 6.

Castigliones team also interviewed former USC head coach Tom Herman for the vacant head coaching position.

Herman, who has served as USC’s offensive coordinator since 2013, is under contract through 2018, and he could be hired on a full-time basis, according a person familiar with Herman’s plans.

Former Alabama coach Nick Saban was the No. 1 choice for the post, according in an ESPN report, but Castiglio has been making an effort to recruit candidates from other programs.

Castoglio has also been trying to recruit Oklahoma assistant and current Auburn offensive coordinator Brent Pease, a person said.

The Sooners currently have four vacant head-coaching positions: Oklahoma assistant coach Joe Vitt, Oklahoma defensive backs coach and coordinator Chris Petersen, and Oklahoma offensive coordinator Brady Hoke.

The position is expected to be filled by either Castiglioli or a candidate with a proven track record.

He also could announce his decision on a hiring spree in the coming weeks.