A group of mayors dedicated to the legalization of gay marriage has added five co-chairs, four of which come from states that exclude gay couples from marriage.

Mayors for the Freedom to Marry announced Monday that Julian Castro of San Antonio, Eric Garcetti of Los Angeles, Michael Nutter of Philadelphia, Kasim Reed of Atlanta and Greg Stanton of Phoenix would join current chairs Michael Bloomberg of New York, Thomas M. Menino of Boston and Annise Parker of Houston.

The organization also announced that it has grown from 80 mayors in 2012 to 350 mayors representing 35 states and the District of Columbia.

“I'm proud Los Angeles has led the way on marriage for same-sex couples, but we must extend our fight well beyond our city limits,” Garcetti said an emailed statement. “Every American is entitled to the promise on which our nation was founded – that all of us are to be treated equally. The momentum behind the freedom to marry is bringing us closer to achieving the American ideal, and I look forward to partnering with my fellow mayors through this important effort.”