Moore explained that she watched the reality series Sarah Palin's Alaska on a nightly basis for months in order to best imitate the former Alaska governor's speaking style.
"I used to watch it at night. I did everything I could, absolutely everything I could," the Oscar-nominated actress revealed to Access Hollywood Live. "I only had two months to prepare. It was pretty brief preparation time, so I listened to her book on tape."
She continued: "Everything's on YouTube. Everything's documented, so all of her media appearances, all of her speeches, the debate.
"I'd listen to it when I was running, I'd listen to it inside the car, I'd work with a vocal coach. It was pretty intense. I did nothing else for those two months."
Moore went on to insist that she undertook the months of research because she was determined for her portrayal of Palin to be "as accurate as possible".
"It was only four years ago, so people remember everything," she commented. "So when you're playing somebody who's a living figure and culturally significant figure, you better try to get it right."
Game Change is based on a book of the same name by journalists John Heilemann and Mark Halperin about the 2008 presidential election.
Ed Harris portrays John McCain in Game Change, while Woody Harrelson stars as McCain advisor Steve Schmidt and Tiffany Thornton plays the candidate's daughter Meghan McCain.
McCain and Palin have both insisted that they will not watch Game Change and have urged their supporters to also boycott the HBO film.
Several of Palin's former campaign aides have also slammed Game Change, calling the television movie "sick" and inaccurate.
Game Change has been defended by its screenwriter Danny Strong, who insists that there is no political bias in the film.
Game Change airs on HBO on March 10. It will air on Sky Atlantic in the UK.
Watch a teaser trailer for HBO's Game Change below: