Boise State and Memphis are among the schools being discussed by the Big 12 as it considers a possible second round of expansion, sources tell CBS Sports.

Big 12 sources have said publicly and privately in recent days that the conference is not necessarily done expanding despite formally inviting BYU, Cincinnati, Houston and UCF on Friday.

Any further expansion would most likely come after 2024. Commissioner Bob Bowlsby said Friday that BYU would join the conference in 2023. The other three programs will join "no later than" July 1, 2024.

Sources stressed Boise State and Memphis are among several schools being discussed. It has long been known that Boise State is on the Big 12's list of potential future additions.

"We're always going to be aware of opportunities as they present themselves," Big 12 commissioner Bob Bowlsby said at a Friday during a Zoom press conference, citing "the fast-changing athletic environment."

Further Big 12 expansion would bring the once-beleaguered conference to at least 14 members. If Boise State and Memphis were to be added, the Big 12 would virtually corner the market on available Group of Five schools that have played in New Year's Six bowls.

Boise State played in three Fiesta Bowls from 2007-14. Memphis played in the 2019 Cotton Bowl. Houston (five), Cincinnati (three), UCF (two) and BYU have combined for 11 of what are now referred to as New Year's Six bowls.

If those two teams were admitted to the Big 12, there would only be three Group of Five programs remaining that have appeared in New Year's Six bowls: Hawaii, Northern Illinois and Western Michigan. At that point, the Big 12 could make an even stronger case for remaining a Power Five conference.

Boise State, if it joins, would be a travel partner with BYU in the Big 12. Provo, Utah, is otherwise 1,000 miles from the nearest Big 12 campus, Kansas City. Boise State and BYU have played in football for the last nine years.

Memphis would add another quality basketball program to a league that already boasts Cincinnati, Baylor, Houston, Kansas, Kansas State, Iowa State and Texas Tech.

Texas Tech AD Kirby Hocutt said Saturday that "unnamed schools" were possibilities for further Big 12 expansion. Hocutt made the comment during halftime on the school's radio broadcast of the season opener against Houston. He added that Big 12 expansion could be an "8-10 year process."

Baylor AD Mack Rhoades on Thursday told "Whatever happens in the future, that doesn't preclude [us] from another step. Not saying that would happen, but it wouldn't, I think, preclude from another step, another phase [of expansion]."