The American Athletic Conference has discussed adding Boise State as a 12th football member, sources tell CBS Sports. Documents obtained by CBS Sports also indicate these conversations have taken place.

A potential move by Boise State could destabilize the Mountain West and strengthen the AAC's access to the College Football Playoff whether or not the field expands beyond four teams in the future.

Boise State has not yet moved because it has failed to find a geographically-desirable conference as a home for its other sports. The AAC would accept Boise State as a football-only member. The league has been playing with 11 football teams since UConn left last year.  

Boise State had been in discussions with the American earlier this year about a move, sources tell CBS Sports. The talks heated up again this fall.

"[The interest] went away because they couldn't find a place for their other sports," said a source familiar with the discussion who requested anonymity because of the sensitive nature of the talks. "If they could find a place for the other sports, it might have been done in the spring. Hell, they might have been [in the American] this fall."

Perhaps the most comfortable fit for Boise State's other sports would be the Big West, an 11-school Division I conference that does not sponsor football. Mountain West football member Hawaii plays basketball in the Big West.

Boise State sponsors 16 sports after cutting baseball and swimming & diving earlier this year.

The Broncos would prefer their other sports not play in the far-flung AAC. The closest American school to Boise State is Tulsa, which is 1,500 miles away.

Boise State football coach Bryan Harsin urged the school to leave the Mountain West in September as revealed earlier this month by publishing a series of emails.

AAC commissioner Mike Aresco had no comment when reached by CBS Sports. Mountain West commissioner Craig Thompson said he had no knowledge of the AAC's current interest in Boise State.

"We'll just let it play organically because [Boise State will] have to answer the other people in the membership if anybody asks them and we'll leave it there," Thompson told CBS Sports.

In February, former Boise State president Bob Kustra vetted the two commissioners in an email to current Boise State president Marlene Tromp. That communication was obtained by CBS Sports through a Freedom of Information Act request.

"I have been thinking about our conversation this morning, pros and cons," Kustra wrote. "In addition to the factors we discussed regarding this decision, the leadership of the conference is key."

Kustra favored Aresco over Thompson. While that was not specifically clear from the email, sources tell CBS Sports the two spoke about Boise State's place in the AAC.

Three other emails from Boise State obtained by CBS Sports contain Aresco's email address but the language surrounding that address has been redacted.

"Play the American Conference off the Mountain West, that's how [Boise State] got into the Mountain West," another source said. "Mike is a great guy. At that time and ever since, the impression I got from [Tromp] … was it just wasn't practical for all sports."

Boise State has been a member of the Mountain West since 2011 after leaving the WAC. There was a brief dalliance with the old Big East -- headed by Aresco -- in 2012. Boise State committed to a July 1, 2013 entry into the Big East but pulled out in December 2012. All the while, it has been the flagship program of the Mountain West playing in five football championship games, winning three league titles and playing in the 2015 Fiesta Bowl.

Boise State receives more TV revenue than its Mountain West peers because of that flagship status. That disparity has long been sticking point with some conference members. In January, the league signed a new contract with CBS and Fox for a reported $270 million over six years.

A Boise State official projected an increase of $4 million in media rights revenue and NCAA distribution with a move to the American, an email obtained by the Idaho Press shows.

Tromp provided the following statement to CBS Sports: "College athletics today is a very fluid environment. As we've said in the past, it is our responsibility to continue to look for opportunities to advance Boise State Athletics and to compete at the very highest levels. We respect our colleagues in the Mountain West and are proud to be members of the league."

Aresco updated AAC athletic directors on the Boise State situation within the last month, sources tell CBS Sports.

One reason for a possible pause in talks is that Boise State is searching for a new AD. Curt Apsey resigned in October to move into a fundraising role.

Boise State football chief of staff Brad Larrondo suggested Apsey "evaluate best conference placement for football program under current FBS football model with a move to the American Athletic Conference being the top priority," according to an email obtained by the Idaho Press.

In September, Harsin emailed university leaders the following, according to the Idaho Press: "I am 1000% convinced we need to make this move for football."

While he is not specific about the conference, Harsin is believed to be talking about the American.

There is extensive history here. When the CFP formed in 2014, the Mountain West and American were considered the two best Group of Five conferences to compete for the automatic New Year's Six bowl berth that goes to the highest-ranked conference champion of those five leagues. Since then, the American has dominated that space, grabbing a New Year's Six bowl in five of the seven years of the CFP. The Mountain West has qualified for one -- Boise State in 2014.

Adding the Broncos would further tip the scales in the American, which as self-labeled itself a member of the "Power Six".

Harsin has successfully built on the winning foundation laid by coach Chris Petersen. Of the remaining 11 Mountain West football schools, the last one to appear in a major bowl game was Hawaii 12 years ago in the 2008 Sugar Bowl. Boise State has appeared in three Fiesta Bowls since 2007.

The attempt by the Big East to lure Boise State eight years ago was part of a larger effort to form a coast-to-coast conference from California to Florida to the Northeast. But when Big East basketball broke off, the American formed in 2013 with schools from Conference USA and the old Big East. At that point, the schools such as TCU (which landed in the Big 12), San Diego State and Boise (which stayed in the Mountain West) found homes after turning down the Big East.

"It just wasn't practical for [Boise State to move] all sports," said a person involved in those original Big East talks. "It didn't work out. We didn't want to send our volleyball team to Central Florida."

However, that same source said, "If I was there [now], I'd be doing handstands trying to figure out how to do it."