Actor Brad Pitt has donated $100,000 to pro-gay marriage campaigns in the four states holding referendums on the issue Tuesday.

“It's unbelievable to me that people's lives and relationships are literally being voted on in a matter of days,” Pitt said an e-mail to members of the Human Rights Campaign (HRC), the nation's largest gay rights advocate.

“If you're like me, you don't want to have to ask yourself on the day after the election, what else could I have done?”

HRC said the Fight Club star was matching contributions of others giving to the campaigns in Maine, Maryland, Minnesota and Washington state.

Voters in Maryland and Washington are deciding the fate of gay marriage laws approved by lawmakers. Minnesotans are considering a constitutional amendment which would limit marriage to heterosexual couples. And Maine's ballot includes a measure seeking to legalize marriage for gay couples in the state.

“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 he same protections as everyone else,” Pitt added.

“Every person's right to life, liberty and the pursuit of happiness is enshrined in our country's Declaration of Independence, but powerful, well-funded groups are flooding the airwaves with lies trying to take away those rights from certain people … and we can't stand for it.”

A longtime supporter of marriage equality, Pitt also gave $100,000 to fight Proposition 8, California's 2008 voter-approved gay marriage ban.

(Related: Brad Pitt still for Obama, gay marriage despite mother's disagreement.)