Amazon.com founder Jeff Bezos waded into a developing corporate culture war over gay marriage Friday with a $2.5 million donation to keep same-sex unions legal in Washington, becoming the latest in a list of high-profile executives to take public stands on a hot election issue.

Bezos joins Microsoft co-founder Bill Gates and companies like Starbucks Inc. and Nike Inc. with support to the campaign to uphold Washington's law. And while fast-food chain Chick-fil-A set off a furor opposing same-sex unions this month, other companies — including big names like General Mills and Nabisco — are brushing off fears that support for gay marriage could hurt their bottom line.

Gay rights advocates say the activism sends a strong message.

"Companies are a bellwether of what is in the mainstream," said Marc Solomon, the national campaign manager for Freedom to Marry, a New York-based group that advocates for same-sex marriage. "When you have some of the mainstays of corporate leadership stand up, that's important. It sends a powerful message about where our society is right now."