NBC, which airs the annual holiday spectacular, and Fox had been in negotiations for some time to nail down the details of the appearance, including wardrobe and choreography, according to E! Online.

While neither network will comment on the change of plan, E! Online quoted an unnamed source at NBC who said the problem arose because Macy’s invited the “Glee” cast without clearing it with the network.

A source close to the parade told E! Online that NBC ordered organizers of the long-running Thanksgiving tradition to withdraw the invitation because “there was concern that featuring the entire cast of a rival’s show amounted to outright promotion.”

When questioned about the difference between the “Glee” cast performing and the participation of contestants from Fox’s “American Idol” in the past, another NBC source explained that “Idol” contestants have only been invited after they’ve left the show.

Although the reversal no doubt comes as a blow to the talented “Glee” cast, who had already been informed that they would be performing, the show’s creator Ryan Murphy isn’t taking the slight lying down, telling EW.com, “I completely understand NBC’s position, and look forward to seeing a Jay Leno float.”

Ouch!

And now here’s a carrot for all the disappointed fans out there: Murphy also took the opportunity to confirm to EW that a “Glee” tour is in the works and will most likely hit the road next spring, after the show wraps for the season.

In the meantime I guess my fellow Gleeks and I will just have to be happy with watching the show every week. Speaking of which, folks who’ve had the chance to see tomorrow night’s episode have been singing its praises, with particular plaudits for the cast’s version of Avril Lavigne’s “Keep Holding On.”