Gay-marriage advocates in Washington state received a big boost on Friday in their battle to defeat a referendum to repeal a new state law allowing same-sex marriage: a $2.5 million donation from Amazon.com founder and CEO Jeff Bezos and his wife, Mackenzie.

Associated Press

“The extraordinary contribution from Jeff and Mackenzie Bezos will make an enormous difference for our campaign to defend Washington’s marriage law,” Zach Silk, the campaign manager for Washington United for Marriage (WUM), said in a statement. The ballot measure, called R74, will decide whether a law passed by the state’s legislature earlier this year will remain on the books. The issue is also on November ballots in three other states – Maryland, Maine and Minnesota. Voters in a string of states, most recently North Carolina, have banned same-sex marriage; it remains legal in six states because of court or legislative action.