He tweeted the news on Saturday in response to a follower's question for clarity on reports that he's returning to the show.
Contrary to Harmon's tweet, an individual with knowledge of the situation confirmed to the TheWrap that the production is exploring ways to bring back Harmon, but that nothing has been finalized and no deals have been signed, though they're expected to close early next week.
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Fans of the show would probably welcome Harmon back to the fold. After the showrunner was replaced on Season 4, the show did take on a different tone and a more traditional sitcom structure. Additionally, Harmon was always clear about the four year plan for the characters (which included graduation on Season 4) but Year 5 has been a mystery.
It could be very helpful to bring Harmon back for that direction alone, something he has probably plotted out in his mind already.
Harmon was let go amid low ratings, feuding with Chevy Chase (who left last season) and a reputation for running late on scripts. He was replaced by David Guarascio and Moses Port, who focused more on relationships between the characters and less on the narrative oddities for which Harmon was celebrated. They didn't take out all the weirdness, of course: One show this past season featured puppet versions of the cast.
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Despite continued low ratings, the show was picked up for a fifth season earlier this month.
Sony Television, the show's producers, declined to comment and NBC did not immediately respond to requests for comment.