NBCUniversal and Charter Communications are in a carriage-negotiation standoff that could see millions of customers lose access to NBCU-owned channels beginning Jan. 1.

With both parties at an impasse, Comcast-owned NBCU has prepped a marketing campaign designed to appeal to Charter customers to pressure the cable provider into taking a more flexible negotiating stance. That campaign was set to launch late Thursday afternoon with a crawl that would run across the screens of Charter’s Spectrum customers watching NBCU channels, alerting them to the possibility of a programming blackout.

Sources tell Variety that Charter, which earlier this year completed a merger with Time Warner Cable, has rejected a package price for NBCU’s channels similar to that paid by other distributors, and that negotiations have stalled completely. The current Charter-NBCU deal is set to expire Jan. 1, raising the possibility that NBCU channels would be blacked out on Charter’s Spectrum service at that time. Among NBCU’s cable channels are Bravo, E!, Syfy, USA, MSNBC, CNBC, and Oxygen. Those channels reach 16 million subscribers via Charter Spectrum, making Charter NBCU’s third largest distributor. In a blackout, Spectrum customers in New York and Los Angeles would presumably lose access to NBCU-owned local NBC and Telemundo stations, affecting 2 million customers.

“NBCUniversal values its partnership with Charter Spectrum, our third largest distributor,” an NBCU spokesperson told Variety in a statement. “Charter Spectrum has been unyielding in its demand for terms superior to those agreed to by the rest of the industry, including larger distributors. Given this position, we feel the responsibility to inform viewers that Charter Spectrum may drop NBCUniversal’s networks at the end of the year, including NBC, Telemundo, USA, Bravo and hit shows including the #1 show on TV—Sunday Night Football, WWE, the Golden Globes, This is Us and more.”

NBC will host a high-stakes “Sunday Night Football” matchup between the Green Bay Packers and Detroit Lions on Jan. 1. The broadcaster also has scripted programs “This Is Us,” “Blindspot,” and “The Blacklist” set to resume new episodes in the first two weeks of January, and will broadcast the Golden Globe Awards Jan. 8. USA’s “Colony” and “Suits” as well as Syfy’s “The Magicians” are also set to return in early January.

If a blackout were to occur, it would be NBCU that would initiate one with a decision to cut its feed to Charter.

The NBCU marketing campaign includes a website and phone number it encourages Spectrum customers to call to pressure Charter on negotiations, with graphics and video designed to drive viewers to those outlets.

A Charter spokesperson declined to comment.