From WENN.com

The two Hollywood stars will join The Office actor John Krasinski as co-hosts of a bash in Santa Monica, California to raise money for Elizabeth Warren's Massachusetts senate campaign. The Democrat is up against Republican rival Scott Brown to take the senate seat in Affleck, Damon and Krasinki's home state.

The event will be held at director J.J. Abrams' Bad Robot production studio on 21 May (12).

Damon and Affleck have worked together several times in the past, including co-writing and starring in 1997's Good Will Hunting, which earned them a Best Screenplay Oscar.