Prop. 8 On Broadway: Bradley Whitford, John Lithgow Added To Play's Cast

09/09/2011 03:10 am ET | Updated Nov 08, 2011

NEW YORK -- A new play about the legal battle over same-sex marriage in California keeps attracting big-name talent.

Producers announced Thursday that the cast of "8" will include John Lithgow, Rory O'Malley, Bradley Whitford, Bob Balaban, Matt Bomer, Campbell Brown and Larry Kramer.

That's on top of cast members already revealed, including Anthony Edwards, Morgan Freeman, Cheyenne Jackson, Christine Lahti, Rob Reiner, Yeardley Smith and Marisa Tomei.

The play, by Oscar-winning screenwriter Dustin Lance Black, will be performed as part of a fundraiser at the Eugene O'Neill Theatre for one night only – Sept. 19.

Proposition 8 is the measure approved by California voters in 2008 that bans gay marriage in the state. A federal judge struck down the law last year.

The play is based on the trial transcript and interviews.