Peter Sarsgaard in talks to play Robert Kennedy in 'Jackie'
The film will focus on the first four days after President John F Kennedy's assassination in Dallas in 1963, as Jackie attempts to deal with the tragedy, reported Digital Spy.
Natalie Portman is set to star Jackie Kennedy in the film.
Darren Aronofsky and then-partner Rachel Weisz were developing the project previously in 2010, but the film was held up after they split.
Aronofsky is still on board as producer.
The film is expected to begin shooting in the next couple of months.