"I am proud to lend my voice — and support — to those who defend him," the "Batman" star continued. "Priorities USA Action is doing a great job of protecting the values I believe in. I am happy to help them and I hope others will join me."
Priorities USA has been outpaced thus far by its Republican counterparts — the group supporting Mitt Romney's efforts raised $20 million to the Democrats' $6 million in June — but more Hollywood stars are opening their checkbooks for the group. Other donors have included comedians Bill Maher and Chelsea Handler, directors Steven Spielberg and J.J. Abrams and producer Jeffrey Katzenberg.