Shirley MacLaine has turned down the role of an alcoholic grandmother in husband and wife directing team Melissa McCarthy and Ben Falcone's debut Tammy. Susan Sarandon is now in talks for the role.

The story will follow the misadventures of a woman who is laid off from her fast food job, only to discover that same day her husband is cheating on her. She decides to take a road-trip with her foul-mouthed, diabetic grandmother who has a taste for whiskey. Melissa McCarthy is playing Tammy.

Kathy Bates has also joined the comedy, and will co-star as the grandmother's lesbian friend who saves the two leads from a couple of rough spots in their journey across America.

Melissa McCarthy recently had this to say about her character.

"[She's] kind of falling apart and has to get out of town but her car is broken down. So she ends up on the road with her grandma, who has a drinking problem for sure. They both have their issues they're not acknowledging and they're leaving town without knowing where they're going. I love that there's something that happens in a car with people where all bets off. You're off your rhythm, off your schedule, you're forced to be completely adaptable or die."

Melissa McCarthy and Ben Falcone also co-wrote the screenplay. Will Ferrell and Adam McKay are producing with Kevin J. Messick, Chris Henchy and Rob Cowan.

No production schedule has been released.