In 2009, the Hugo director was chosen by Universal to direct the Sinatra film. It was said then that Field of Dreams screenwriter Phil Alden Robinson was attached to write the project, but it now seems that is no longer the case.
"I'm talking to one or two writers now," Scorsese told Entertainment Tonight. "The problem is the biography. Where do you start?
"Hugo took up so much time that I now have to settle in. I met this writer who I think could do a lot with it, but [we] have to get a hold of the story. It's too unwieldy.
"I'd love to tell the whole story, but the idea of art is to figure out where to start because we can't tell his whole life story. If we told the whole story of Sinatra, it would be 15 hours - then you've got something like a miniseries, along the lines of Boardwalk Empire."
When Scorsese was asked to share his thoughts on casting an actor to portray Sinatra, Scorsese said: "[Leonardo DiCaprio's] always talked about doing it, but what if the story takes you in a completely different way?
"We could go for an unknown. Maybe the person who plays him isn't important. Maybe it's distracting to have a star in that role. Yet, you can't have someone else sing! It's got to be Sinatra's voice.
"It's tricky. It's filled with problems - and whatever you do, there's always going to be people who don't like it, so you have to find something special. And I think I've found it. Now's the time to execute it on the page."
Watch the trailer for Hugo below: