Talks about a partnership between the Big 12 and the Pac-12, which had been discussed extensively the past two weeks, have officially ended, sources told ESPN.

Officials from the Big 12 told Pac-12 officials on Monday that they're no longer interested in exploring the partnership, sources said.

A Big 12 source said that the deal didn't work for the Big 12 for "a multitude of reasons," which included the fact that any potential deal wouldn't have driven much revenue for the league. "It just didn't work," the source said.

There's been at least three Zoom calls between top league officials in the Big 12 and the Pac-12 and other calls between other factions of the league -- including legal -- to discussion different options. The extent of the conversations had not been previously reported.

A Pac-12 source briefed on the conversations said that the Big 12 had expressed interest on Friday in possibly exploring a full merger. The Big 12 source said of the three options laid out by the Pac-12 -- pooling rights, a scheduling concept or fully combining the leagues -- that the only scenario that could have potentially driven value because of the sheer numbers of schools and populations areas was a full merger of the leagues.

The Pac-12 source indicated the Big 12 was interested in that option. A Big 12 source said the Big 12 needed more time to explore that option further, which it did over the weekend and decided not to explore any options further.

The Pac-12 source said that the Pac-12 was skeptical of the full merger because the leagues' media rights expire at different times. A Big 12 source countered that the Pac-12 had expressed ways they could work around that.

"Because the Big 12 media rights can't be negotiated until 2024, Pac-12 schools have no motivation to join the Big 12," said a Pac-12 source. "The Pac-12 has announced that they're staying together and are in the middle of media rights negotiations."

The Pac-12 has been exploring all options after the sudden departures of UCLA and USC have left the league without two of its top brands and no toe hold in the Los Angeles media market. The league has just two full years remaining on its underwhelming television deal, and Commissioner George Kliavkoff has been diligently exploring creative ways to generate revenue.

That's included conversations with the ACC about some sort of scheduling arrangement, but sources have told ESPN that the financial reality of that potential partnership also projects to underwhelm.

The Pac-12's expiring contract and few options to generate revenue continues to perpetuate the notion that the Pac-12 is the most vulnerable of the Power Five leagues. With the Big Ten nabbing two of the league's top properties and cutting the potential value of the upcoming television contract significantly, the reality of the Pac-12 needing to fight off potential poachers could emerge.

Both Oregon and Washington have participated in the College Football Playoff and aren't bound by a grant of rights after the league's TV deal ends. Also, the Big 12 has monitored through backchannels the potential of adding Pac-12 schools Arizona, Arizona State, Utah and Colorado, which is a former Big 12 member.

New Big 12 Commissioner Brett Yormark has maintained that the league is "open for business" and the conference has stressed that it plans to be aggressive about potential additions.

"We will leave no stone unturned to drive value for the conference," Yormark said at media day. He added: "There is no higher priority than to best position the Big 12 for its upcoming multimedia rights negotiations. Everything we do must create momentum for those negotiations."

On July 5, the Pac-12 announced that the league's Board of Directors authorized the league to immediately begin negotiations for its next media rights agreements. That's left the league exploring different and creative options to drive revenue through partnerships.