According to the Hollywood Reporter, Davis, who also appears in HBO's "In Treatment," will join actor Dennis Quaid, who will portray former U.S. President Bill Clinton in the Peter Morgan film. Moore bowed out of the production due to a scheduling conflict with the film "The Kids Are All Right."

Frost/Nixon and "The Queen" actor Michael Sheen is signed to repeat his work as former British Prime Minister Tony Blair for screenwriter Morgan. Actress Helen McCroy, who portrayed Cherie Blair in "The Queen," will again co-star with Sheen.

"The Special Relationship," which was to mark Morgan's directorial debut, will now be helmed by Richard Loncraine. The film explores the political relationship of the leaders on both sides of the Atlantic. It is the third installment in Morgan's Blair trilogy, which also includes "The Deal" and "The Queen."

Filming is set to begin July 20 in London, just prior to Davis' summer hiatus from God of Carnage, which begins July 27. The Tony-winning play, and its starry cast, will resume performances on Broadway Sept. 8.