At the film's TIFF premiere, Larraín told Vanity Fair's Julie Miller that when producer Darren Aronofsky suggested the project to him, Larraín responded that he would only direct the film if Portman portrayed the title character. "I didn’t see anybody else playing her,” he told Miller. "It was a combination of elegance, sophistication, intelligence, and fragility. Beauty and sadness can be something very powerful in our culture."

Here's a further excerpt from Miller's article:

At the time, Larraín did not really love the script for the project; did not feel a personal connection to Kennedy; had never made a film about a female character; and honestly did not like traditional biopics. But he was certain of one thing he would do if Portman agreed to star.

“I told her, ‘Look, I have not talked to the writer—but if I were to do this movie, I would take out all of the scenes you are not in.’”

The result is a fragmented retelling of the four days following John F. Kennedy’s assassination, told through the feverish prism of post-traumatic stress disorder. Larraín takes the same artistic liberty with Neruda, which doesn’t tell a linear life story so much as it gives viewers an original, entertaining experience that encapsulates the subject’s persona. In Neruda, Larraín does so by using the poet’s love of crime novels to fashion the film into a detective story, starring Gael García Bernal, about an inspector trying to track down his exiled title subject.

“When you make a movie about a poet from the 40s, my biggest fear is to make a boring movie,” Larraín explains. “We create a fiction over a non-fiction. I don’t expect these to be used as educational tools. I remember I was an exchange student in the U.S. for half a year, and I would go to high school and they would show movies about the Civil War, movies about Abraham Lincoln. And all of those movies were terrible. . .We worked hard not to make [these films] entertaining just to be entertaining, but there are a lot of interesting, fun elements there, and they are beautiful and very simple but sophisticated. They are character studies about a very specific time in these people’s lives, and being fascinated by the characters. What I've learned with cinema is you really have to be fascinated by the characters.”

Before making Jackie, though, Larraín—who did not grow up in the U.S.—had to find his personal connection to Kennedy.

As he told Aronofsky, who urged him to make the project, “I don't know why you are calling a Chilean to make a movie about Jackie Kennedy—but that’s your call.” And after his initial meeting with Portman, the filmmaker realized that his personal connection to Kennedy was still missing.

“I went home and I was like, there’s something else in here. I started Googling and on YouTube I found this White House tour from 1961 that I had no idea existed,” explains the director. “I couldn’t believe my eyes. I couldn’t believe what I was watching. . .She actually raised private money, and what she did was a restoration, going with a team of people all over the U.S. to find furniture that at some point was in the White House but was sold for different reasons. I thought it was just so beautiful the way she did it, and I fell in love with her watching that program—just the way she moved, the fragility, the way she explained things, how educated she was. This idealism that she had. It sounds naive, this Camelot thing to me, but once I got into it I found it very interesting and beautiful and deep even though I’m not American.”

Scarface remake would have been Larraín's "dream project"