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The Human Rights Campaign today announced a $100,000 contribution from the actor Brad Pitt to help fund the organization’s final six days of campaigning for ballot measures in four states that would legalize same-sex marriage.

Pitt has agreed to match donations to HRC up to $100,000, the organization said in a news release. HRC, the nation’s oldest gay-rights organization, is working to pass ballot referendums in Maryland, Maine and Washington State that would permit same-sex marriage and is also opposing an amendment to the Minnesota constitution that would define marriage as a union of one man and one woman.

Maryland and Washington passed laws earlier this year creating marriage equality, though petition drives in both states garnered enough signatures to send them to public review for final approval. Maine passed a marriage-equality law in 2009, but it was repealed by a voter referendum later that year.

“It’s unbelievable to me that people’s lives and relationships are literally being voted on in a matter of days,” Pitt said in an email distributed to HRC’s members today. “But that’s the system we have and I’m not going to back down from the fight for loving and committed couples to have the ability to marry.”

HRC says it has spent $5 million on the four ballot measures this year, and $8 million on same-sex-marriage advocacy since 2011. Recent polling has been promising for Maryland Question 6, Maine Question 1 and Washington Referendum 74, while Minnesotans are split about evenly on whether to deny marriage equality.