Stephen Baldwin has been replaced on the set of Nicholas Hytner’s and 20th Century Fox’s “Object of My Affection” after only one day of work. Baldwin was to portray civil liberties attorney Vince (and boyfriend to Jennifer Aniston) in the comedy/drama about a relationship between a straight woman and a gay man. John Pankow, a regular on “Mad About You” but best known for his Broadway and Off Broadway roles (“Amadeus,” “The Iceman Cometh”) will now step into the role. Baldwin and the filmmakers saw the role differently, sources said of the actor’s exit. The project, based on the book by Stephen McCauley, is being produced by Laurence Mark from an adaptation by Wendy Wasserstein. Paul Rudd, Alan Alda, Nigel Hawthorne and Tim Daly.