Missouri handed the right to negotiate and make decisions on behalf of the school's conference affiliation to chancellor Brady Deaton on Tuesday.
With that, it hopes to join the SEC. The conference, though, was Missouri's second choice behind the Big Ten. Remaining in the Big 12 was its last choice. The Big 12 which has lost three members in the last 15 months.
Missouri hoped to join the Big Ten last year but the league instead chose Nebraska. The university official said the Big Ten remains Missouri's top choice but that conference "has no interest."
"That's what's left," the official said, referring to the SEC.
The SEC's athletic directors met on Wednesday, but the possible addition of Missouri was not on the agenda, a source with direct knowledge of the meeting told ESPN.com's Andy Katz. The meeting was called several weeks ago.
SEC commissioner Mike Slive has not ruled out further expansion, and Tennessee athletic director Dave Hart has said the SEC will eventually add members.