As Major League Baseball commissioner Bud Selig approaches the end of his final season on the job, the task of choosing his successor remains far from finished. But there is a growing sense of inevitability among baseball officials that the job will end up going to Selig's right-hand man.

Rob Manfred, MLB's chief operating officer and longtime labor chief, who has Selig's support, has the backing of roughly 20 owners, according to interviews with four high-ranking team executives. And while a formal vote is still likely months away—a candidate must receive at least 23 votes to win the job—a clear rival to Manfred has yet to emerge.

In May, seven owners were tasked with leading the search for Selig's successor. So far they have interviewed Manfred and two other league executives, according to two people with direct knowledge of the process.

The other interviewees are Bob Bowman, president and CEO of MLB Advanced Media and Tim Brosnan, executive vice president for business. The succession committee has also formally interviewed at least two other candidates from outside the commissioner's office, one of these people said.

Larry Baer, chief executive of the San Francisco Giants, has had informal discussions with the committee about the job but has yet to make himself a candidate, one person said.

MLB spokesman Pat Courtney declined to comment, citing the confidential nature of the search.

One potential candidate from outside MLB is Walt Disney Co. DIS +0.55% chairman and chief executive Robert Iger. According to a person briefed on Iger's talks with MLB owners, he is currently discussing the ground rules under which he would become a candidate, as he is wary of vying for a job that Manfred appears likely to win. Another person close to Iger said that the MLB job is one of many post-Disney options he is considering. Iger is also under contract with Disney through June 2016. Selig is set to retire in January 2015 and has been adamant that he won't stay on longer.