EXCLUSIVE: Natalie Portman Admits Playing Jackie Kennedy Was 'Challenging,' Gushes About Hillary Clinton

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Natalie Portman may look like she was meant to play Jackie Kennedy, but according to her, it wasn't that easy.

ET caught up with the 35-year-old actress at the New York City premiere of Jackie on Thursday, where she revealed that she was “nervous” to take on the role.

WATCH: Natalie Portman Is Pregnant With Second Child, Debuts Baby Bump on Red Carpet at Venice Film Festival

"I was very nervous," she confessed. "I mean, people are very aware of what she looked like and what she sounded like and what she moved like. And it's challenging because you want to approximate that as much as possible. And luckily there was a wealth of information out there that I could draw from."

Part of that wealth of information was Jackie's iconic fashion. And while Portman says the film, which picks up after JFK's assassination, isn't "particularly about the clothes," she does admit that the costumes helped her to get into character.

"Of course when you wear clothes or hair and makeup for a character it always helps put you in character and in the mood of where you are, so it's helpful," she said.

While Portman promotes her role, she's also been campaigning in support another former first lady, Hillary Clinton. 

WATCH: Natalie Portman Is Perfectly Poised as Jackie Kennedy in First Teaser Trailer for 'Jackie'

"I'm very excited to see Hillary become president," she gushed. "And it's of course been a disappointing election cycle to hear the vulgarity as opposed to people talking about the issues, [but] I think Hillary has been great about bringing it back to that when there's a lot of noise."

The Oscar winner, currently pregnant with her second child, hit up four different events in the Philadelphia area while campaigning for Clinton on Monday.

See more in the video below.

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