After getting close to pushing the long-in-development project into production, Amblin Entertainment is shutting down pre-production on Aaron Sorkin’s “The Trial of the Chicago 7,” sources tell Variety.

Sources say Sorkin is focusing on his play “To Kill a Mockingbird,” which opens Thursday, while the studio figures out how to move forward on the film. Amblin released a statement on Wednesday saying they are still involved and are giving Sorkin time to finish work on his play.

“Aaron just adapted ‘To Kill a Mockingbird,’ which is premiering on Broadway this Thursday. He is currently evaluating his schedule and commitments to determine the best time and way to make ‘The Trial of the Chicago 7.’ Amblin remains involved as a producer,” Amblin said in a statement.

Amblin had been trying to get the film into production for more than a decade, with Paul Greengrass and even Amblin CEO Steven Spielberg all boarding as directors at one point.

The movie is based on the infamous 1969 trial of seven men charged by the federal government with conspiracy, arising from the counterculture protests in Chicago at the 1968 Democratic National Convention. The trial transfixed the nation and sparked a conversation intended to undermine the U.S. government.

Sorkin, who penned the script, was eventually tapped to helm the film following his directorial debut, “Molly’s Game.” Marc Platt is producing the pic.

The studio had already hired Eddie Redmayne, Sacha Baron Cohen, and Jonathan Majors to star, while Seth Rogen and Joseph Gordon-Levitt were being eyed for possible roles.

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