Jockeying for position and regulatory worries are the order of the day in the

Univision

(UVN)

bidding war.

The Spanish-language media juggernaut has been up for grabs since early this year, when it announced it was putting itself up for sale. Bids are due Tuesday, but after months of wrangling it isn't clear which of the deep-pocketed competitors has the upper hand. Univision is expected to fetch in the neighborhood of $12 billion.

Televisa

(TV) - Get Report

, the large Mexican programming supplier and 11% Univision stakeholder, is leading one bid for the company. The other bidding group comprises private equity players Providence, Madison Dearborn, Thomas H. Lee Partners and Texas Pacific Group, along with media mogul Haim Saban.

Venevision, a Venezuelan programmer and 14% Univision stakeholder, said last week that it has joined with the Televisa bid. It joins

Microsoft

(MSFT) - Get Report

founder Bill Gates' Cascade Investment and private equity players Bain Capital, Carlyle Group, Blackstone Group and Kohlberg Kravis Roberts.

Cisneros-owned Venevision formally announced its intentions on Thursday when it made mention of a programming contract in effect until 2017. Televisa wanted to clarify the state of play, saying in a release that "due to certain uncured and uncurable breaches by Univision of that agreement, Televisa believes itself to have the right to terminate the agreement and is pursuing that position in its pending litigation with Univision."

Indeed, there is no uncertain amount of interdependency between the two groups. Univision needs to program its various networks, while Televisa and Venevision need to sell that programming. Univision's properties include its three networks (Galavision and TeleFutura are the two others) along with TV and radio station properties and a host of ancillary businesses.

But the message from Televisa served as a reminder of the tension among the parties. Televisa's rival bidder may take some pause at the notion that the programming pipeline may be in some jeopardy or that purchasing the company might include the possibility of protracted litigation.

And regulatory issues are reportedly creeping into the mix as bids are finalized. Under U.S. law, Televisa may not hold more than a 25% ownership stake in the company because of foreign media-ownership restrictions. Those restrictions forced both Venevision and Televisa leadership to team up with their U.S.-based partners.

And the Federal Communications Commission is likely to take a hard look at any deal that emerges with either bidder.

The New York Times

, citing people involved in the process, reported Monday that the auction has become focused in recent days on the regulatory hurdles the two suitors may face. One group, the

Times

story said, could face FCC challenges over foreign ownership, while the other may face FCC pushback on "concentration concerns." Many of the private equity players, such as Providence, already have substantial media holdings in the U.S.

Strategic interests including

Disney

(DIS) - Get Report

,

CBS

(CBS) - Get Report

and

Time Warner

(TWX)

have begged off the auction, citing the high price tag on the company. UBS is overseeing the process for Univision.

On Monday, Univision shares dropped 38 cents, or 1%, to $35.37.