Bryan Cranston detailed the intensive process he went through in order to reprise his role as president Lyndon B. Johnson at the premiere of HBO’s telepic “All the Way” at Paramount Studios on Tuesday. The actor told Variety he did research even after his Broadway run in the Tony Award-winning political drama directed by Jay Roach and written by Robert Schenkkan.

The play adaptation continue’s Roach’s fruitful collaboration with HBO on politically-themed material such as “Recount” and “Game Change.”

“[I am] always going back to the actual text, whether it’s the play or whether it’s the screenplay,” Cranston said, citing literary works by Robert Caro, Doris Kearns Goodwin and Joseph Califano as research material. “Then slowly but surely, that character — which started outside of you — slowly starts to come.”

Cranston added, “Almost like osmosis, it comes in and all of a sudden you’re thinking like him; you’re thinking through your LBJ filter. Then you know you have the character, and you own it.”

Although the six-time Emmy-winning actor applied this all-consuming method to his roles, he readily rids himself of the character once the performance has wrapped. Unless, of course, he’s asked to revisit the character for a role reprisal.

“I enjoy playing around with this character because he was bigger than life,” said Cranston, offering up his best LBJ impression. “But when it’s over, I leave it. I don’t want to take it with me.”

“All the Way,” which chronicles President Johnson’s turbulent first year in office, broke Broadway box office records and picked up a Tony Award for best play and best actor. Soon thereafter, the playwright adapted the story for the small screen — a process he terms as a “labor of love.”

“You so rarely get a second bite of the apple,” said Schenkkan. “We knew we were not just going to shoot the play — this was going to be a complete cinematic re-imagination of this story, and that’s exactly what we’ve done.”

Schenkkan said that when he began discussing the project with producing partner Steven Spielberg, recruiting Cranston to lead in the role of LBJ was “never any question.” Spielberg, an exec producer of the telepic, made a surprise appearance for the L.A. premiere as well.

Other celebrity attendees at the “All the Way” L.A. premiere included co-stars Anthony Mackie, Melissa Leo, Bradley Whitford, Ray Wise and Spencer Garrett and exec producers Darryl Frank and Justin Falvey. 

“All the Way” premieres May 21 on HBO at 8 p.m.