Best known as the star of "Will & Grace," McCormack will play presidential contender Joseph Cantwell in "The Best Man." The role was played by Cliff Robertson in the 1964 film adaptation and by Chris Noth in the 2000 Broadway revival.
McCormack made his Broadway debut in "The Music Man." He returned to New York for the American premiere of Neil LaBute's "Some Girl(s)" and appeared in David Mamet's "Glengarry Glen Ross" at the Stanley Industrial Alliance Stage.
"The Best Man" is to begin rehearsals Jan. 30, with the first preview performance set for March 6. An official opening is set for Sunday, April 1 at a Shubert Theatre to be announced.