Sorkin's project, titled "More as This Story Develops," will star Tony Award nominees Jeff Daniels (God of Carnage), Alison Pill (Lieutenant of Inishmore) and Sam Waterston (Abe Lincoln in Illinois), as well as West End actress Emily Mortimer (The Merchant of Venice, The Light) in the female lead. Josh Pence, from "The Social Network," has also signed on to the project that Sorkin will produce alongside Scott Rudin.

"More as This Story Develops" centers on cable news anchor Will McCallister (Daniels) and the show's female executive producer, MacKenzie (Mortimer).

As previously reported, Pill, also currently in The House of Blue Leaves, has signed on to play Maggie, an associate producer on the assignment desk, and Olivia Munn will play a "sexy financial analyst" on the same cable network as McCallister.

Gallagher Jr. will play Jim, who comes to work on McCallister's show and develops a crush on Maggie. Pence will play Rob, senior producer in charge who has been in a relationship with Maggie for five months and starts to become jealous of Jim. Sadoski will play McCallister's former executive producer who left the network to work for a new show.

Gallagher Jr. won the Tony Award in 2007 for his performance in Spring Awakening. Sadoski was nominated for a Tony in 2009 for his performance in Reasons to Be Pretty.