The nation’s largest gay rights group announced Wednesday that Pitt agreed to match contributions from the group’s members up to $100,000.

“It’s unbelievable to me that people’s lives and relationships are literally being voted on in a matter of days,” Pitt wrote in an e-mail going out Wednesday to supporters of the gay rights group. “In Maine, Maryland, Minnesota and Washington, voters will go to the polls to decide if gay and lesbian couples – our friends and neighbors – are worthy of the same protections as everyone else.”

The ballot measures in Maine, Maryland and Washington seek to legalize gay marriage, while the Minnesota initiative would ban same-sex marriage. The Human Rights Campaign has already donated $5 million to the state campaigns. Pitt’s donation will be split evenly among them, and organizers hope it will spur more giving.