How Dennis Quaid Brought Ronald Reagan to the Screen in New Biopic: 'I Was Scared to Death' (Exclusive)

Despite an illustrious career in film spanning nearly 50 years, Dennis Quaid still gets nervous about approaching certain roles.

During a conversation with PEOPLE at CinemaCon in Las Vegas on Thursday, April 11, the 70-year-old actor admitted that he initially felt some fear at the prospect of playing the 40th president of the United States in the upcoming biopic Reagan.

But he had some time to prepare. "I think it was end of 2017, that [producer Mark Joseph] actually came to me and said, 'We want you to play Ronald Reagan,' " Quaid recalls.

His first reaction was to say, "You're kidding me," as the actor explains, "I felt like I was nothing like Reagan, even though he was my favorite president and everything."

"But really, I was scared to death about doing it," Quaid adds.

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Quaid goes on to say he "had to get past" his "awe" over the late actor-turned-politician, who died in June 2004 at age 93, in order to play him.

"I didn’t know how to penetrate that, somebody so well known. I didn't want to do an impersonation," he tells PEOPLE. "But I went up to the Reagan ranch and that's what sealed the deal for me because I could feel him up there. And he was a really humble, humble guy."

"He wasn't a rich guy. He bought that place up there right after his governorship and they got a King's size bed, but it was two single beds zip-tied together," Quaid continues. "The house is all about 1,500 square feet, and he did all the work himself. He could feel it."

An official synopsis of the upcoming Sean McNamara-directed film, which PEOPLE shares exclusive first photos from, describes Reagan as a story that "follows the path of a young boy from the dusty roads of Dixon, Illinois, to Hollywood, to the Presidency of the United States and the world stage."

"Ronald Reagan's story is told through the voice of former KGB agent Viktor Petrovich, who was assigned to follow Reagan when he first came to the attention of the Soviets while an actor in Hollywood," the synopsis continues.

"Reagan begins with an aging Petrovich, now 90 years old, being visited by an up-and-coming Russian leader who wants to know how the Soviet Union was lost," the synopsis adds.

It concludes, "Petrovich, the spy who knows everything there is to know about Reagan, begins recounting the tale of his great adversary, the man he mockingly nicknamed 'The Crusader,' beginning in 1922 when 11-year-old Ronald Reagan goes through his first life crisis."

The film also stars Penelope Ann Miller as Nancy Reagan, Mena Suvari as Reagan's first wife Jane Wyman, Lesley-Anne Down as Margaret Thatcher, David Henrie as teenage Reagan, Kevin Dillon as Jack Warner and Jon Voight as Petrovich.

Speaking with PEOPLE at CinemaCon, McNamara, 61, says that while Quaid "studied the real" Reagan, "he made his own version of" the former president.

"Dennis learned all his speeches — I mean, not just the parts we were shooting, but the whole speech," the director says. "We would cut out and use parts of it, but I think it [served] the whole thing creatively for [him] to get the whole thing down. It was amazing."

Quaid tells PEOPLE that he "came to realize" he and Reagan had more in common that he initially realized, even past their obvious backgrounds in acting.

"We both have sunny dispositions down at the bottom of it, so I could really relate on that one," the actor explains. "And really, he was very genuine."

"But being president was the greatest role he could possibly ever have," Quaid adds.

Reagan, distributed by ShowBiz Direct, is in theaters August 30.