It takes a lot of chutzpah to send the President of the United States a letter that reads, “I can and will do more good if I am made a Federal Agent at large” — especially when such a title doesn’t even exist. This request is made by the so-called King of Rock-and-Roll Elvis Presley (Michael Shannon, “Boardwalk Empire”) to Richard Nixon (Kevin Spacey) in a new trailer for Liza Johnson’s “Elvis & Nixon.”

Johnson described the film, which is based on a true story, as a “historical bromance set in 1970.” She told Women and Hollywood that she thinks that audiences will “feel like they’ve been on a journey with Elvis” — and an unexpected one. “We all know that Elvis was the iconic figurehead of the rebellious rock-and-roll youth culture of the 1950s,” she explained, “[so] it’s surprising that by this time he has developed a deep need for the approval of the establishment.”

The “Hateship Loveship” helmer was drawn to the project because of the unusual tone of the script. Johnson said, “I think the story is very funny — there are no jokes in the movie, but there is a lot of comedy in the situation.” The spot for the film highlights the hilarious juxaposition of the conservatively clad White House employees and Elvis’s ultra-cool aviator-wearing entourage. “Put ‘er right here,” an overly casual Elvis tells Nixon, extending his hand.

“Elvis & Nixon” premiered at the Tribeca Film Festival earlier this week and opens in theaters April 22. The film was co-written by Hanala Sagal (“Traumedy Central”).