Friday at midnight, baring any last-minute breakthroughs in negotiations, KDSM, the local Fox affiliate, will no longer be available on Mediacom Communications Corp. cable systems.

Sinclair Broadcast Group, owner of KDSM, had been scheduled to revoke the right of Mediacom to rebroadcast Sinclair stations in Iowa and other states on Dec. 1.   Sinclair eventually extended the deadline until Jan. 5 to give the two sides more time to reach an agreement about how much Mediacom should pay for the right to rebroadcast Sinclair stations.

But now, Sinclair said it no longer expects to reach an agreement with Mediacom.

“As of today, I see no chance of reaching an agreement before the deadline,” said Barr Faber, vice president and general counsel of Sinclair. “There is no point in extending the deadline if there is no chance of reaching an agreement.”

Faber said it’s only in Mediacom’s interest to keep extending the deadline, as that keeps customers from switching to another provider.

Phyllis Peters, communication manager for Mediacom, said her company was caught totally off guard by Sinclair’s announcement that negotiations have failed.

“We have not been notified that there is any reason to close the doors,” she said. “We have made several offers to them, and we will continue to work to resolve this for our customers.”

Sinclair has run advertisements warning Mediacom customers that their stations may no longer be available on cable and suggesting viewers switch to a satellite provider.   Mediacom has responded with commercials arguing that Sinclair is not being fair and does not care about their viewers. The latest ad by Mediacom encourages viewers to call up advertisers of the Sinclair stations. The company has even started a Web site, which among other things provides contact information for some of the advertisers on Sinclair Broadcasting-owned stations.

Faber said Sinclair is trying to notify its viewers before they wake up one morning and they’ve lost Fox.

“There is a benefit to us for our customers to know sooner rather than later,” he said. “If people wake up Jan. 6 and we’re not there, they won’t be able to watch us that day, the next day, maybe for a week depending on when they can find an antenna or switch to satellite.”

Peters said announcing failed negotiations is just a publicity stunt to give Sinclair leverage as talks continue between the two companies.

“They did the same thing Nov. 29, just before the previous deadline,” she said. “It’s a marketing tactic.”

Mediacom has made several proposals to Sinclair, Peters said, one of which would allow for binding arbitration to settle the dispute.

“It’s in both companies’ best interest to put this behind us,” Peters said.

Faber said that it isn’t that negotiations are failing; it’s that negotiations have stopped completely.

“Right now, there are no negotiations going on at all,” he said. “People are going to be mad at both sides of this, and we understand that. We just want to give our viewers as much notice as possible to lessen any effect it may have on them.”

But with the college football Bowl Championship Series championship game airing on Fox Jan. 8, and with new seasons of the popular Fox programs “24” and “American Idol” starting the following week, the two companies agree that failing to reach a resolution would hurt both Sinclair and Mediacom.