The announcement came after Monday's six-hour meeting with the conference's university presidents and the commissioner.
Big 12 commissioner Bob Bowlsby and Oklahoma President David Boren, chairman of the Big 12 board of directors, handled Monday's news conference and frequently cited a spirit of camaraderie among league presidents.
CSU didn't get into a Power 5 conference this time around.
Based on the memo, Boren and Bowlsby were working off a script that included several "do's" and "don'ts" during their presentation, including an effort to quash any conversation that the Big 12 is "dysfunctional".
The Big 12 has been exploring the possibility of expansion for almost three months.
The Big 12 is also just a few years out from passing up on Louisville in its initial expansion push after the conference was raided by the Big Ten, SEC and Pac-12. "This was an endorsement and reinvestment in the 10 that we had".
There were no representatives from CSU or any of the other schools under consideration at the Big 12 meetings.
Texas President Greg Fenves said 10 is the right number for the league. "We remain committed to strengthening our nationally competitive programs in academics and athletics that allow our student athletes to compete on the national stage".
The 11 candidates that the the decision closed down on were the United States Air Force Academy, Brigham Young University, University of Central Florida, University of Cincinnati, Colorado State University, University of Connecticut, University of Houston, Rice University, Southern Methodist University, University of South Florida and Tulane University.
Moving into a Power Five conference for those schools would mean tens of millions of dollars more revenue per year, along with greater exposure and prestige.
Boren stressed that the decision not to expand was unanimous, and expressed deep gratitude to the schools interested in joining the conference.
With so much more money in the system than there was a decade ago, and none of it going to players, schools are essentially building recruiting palaces. - UConn President Susan Herbst, who also serves as chairwoman of the board for the American Athletic Conference. "We've had a lot of success in the Big 12". A legally binding contract is better, but until the Big 12 starts negotiating another television deal or a revision to the current one, locking up the conference beyond 2025 is not a discussion that is taking place, Boren said.
What transpired Monday pretty much confirmed the skepticism I've been feeling about all of this ever since the Big 12 brought expansion back to life in July.
Earlier Monday, the Big 12 announced it would not add to its 10 members.
"We just want to focus on what makes us stronger", OU athletic director Joe Castiglione said Monday. Apparently, the league decided that none of the potential candidates offered that. "We have a strong commitment from every single member of the board to the cohesiveness and stability of the conference".
If Ubben's source was accurate, then shame on the Big 12. "But we do feel it would be wrong to indicate that it is an active agenda item, because it no longer is at this point". The expansion talk blossomed out of the conference missing the first College Football Playoff in 2014.