CBS has warned Dish Network that it will go dark on Thursday if a new carriage deal is not reached by then.

“For six months, CBS has been vigorously attempting to secure fair carriage deals with Dish,” CBS said in a statement. “During that time, Dish has clearly not been operating with the same sense of urgency. In the last few weeks, we have granted two extensions, in the hopes that this would give both parties sufficient time to come to a resolution. The second extension, which protected Dish subscribers’ programming over the Thanksgiving holiday weekend, was the final one. We would very much like to avoid going dark, thereby joining the more than 120 stations Dish has dropped since 2013 alone. Unless agreements are reached, however, our viewers should be prepared to lose CBS from their Dish systems on Thursday evening at 7:00 PM/ET.”

CBS issued the statement to make it clear to Dish execs that there would be no more extensions. In response to CBS, Dish reiterated its past statement on the negotiations:

“Only CBS can force a blackout of its channels. Dish is actively working to reach a deal before the contract expires and has successfully negotiated agreements representing hundreds of stations in recent months that benefit all parties, including our viewers. There is time for the two parties to reach a mutually beneficial deal.”

CBS and Dish execs have been in contact during the past few days and discussions continue. CBS execs are known to be frustrated with what has been described as “foot-dragging” on the part of Dish execs on closing the agreements.

The negotiations for a new carriage agreement have encompassed CBS’ 29 O&O stations as well as Showtime and CBS Sports Network. It’s unlikely that Showtime and CBSN would also go dark on Thursday, but it is a possibility.

The last short-term extension came late last month as negotiations talk progressed, stretching into Thanksgiving weekend. CBS and Dish’s previous deal had expired Nov. 20, covering retransmission consent rights for CBS’ TV stations. When that deal expired, both sides agreed to a five-day extension.

At the center of talks have been Dish’s rights to use CBS’ content, including Dish’s ability to include CBS content in the over-the-top service that it aims to launch, as well as offering out-of-home viewing rights. There’s also likely to be disagreements over Dish’s Hopper DVR service that allows users to record large swaths of primetime with one button.

This isn’t the first time that CBS has complained about Dish moving too slowly. In November, the Eye said Dish “appears willing to drop the most popular programming in its entire channel lineup because it won’t negotiate the same sort of deal that other cable, satellite and telco companies have struck with CBS,” the broadcaster said in a statement.

CBS has aired promos on its stations, rallying viewers to get behind its cause.

Dish is also in the midst of an impasse with with Time Warner’s Turner unit, which eased up last month. Dish and Turner set a short term deal in November restoring CNN, Cartoon Network and other channels to the satcaster’s lineup and extend the carriage agreement for TNT and TBS after Dish dropped CNN and seven other Turner outlets on Oct. 21.

Dish has about 14 million subscribers. It’s not clear how many Dish subscribers in CBS O&O markets would be affected if the stations go dark.