Kluwe’s letter, which has been lauded by many supporters of same-sex marriage since it was posted Friday, has offered a change in perception. The N.F.L. has long fought the stigma of having a homophobic culture. Now, two pro football players have powerfully lent their support for same-sex marriage, taking a political figure to task in the process.

“It was unexpected to a lot of gay people to have someone from the most masculine sports league in the country come to the defense of the gay community and attack this person,” said Cyd Zeigler, a founder of Outsports.com. “It was unexpected, and it was awesome. To see the clear passion for this topic, I think, was energizing.”

The support offered by Kluwe and Ayanbadejo is timely, because Minnesota and Maryland are among four states that will have same-sex marriage votes this November. In Maryland, Maine and Washington, the legalization of same-sex marriage will be on the ballot. In Minnesota, there will be a vote on an antigay marriage constitutional amendment that, if passed, would define marriage as a union between a man and a woman.

“These guys are heroes,” Brian Ellner, a leading marriage equality advocate, said of Kluwe and Ayanbadejo. “This kind of thing has never happened before. It matters because Brendon and Chris are professional athletes who are uniquely positioned to help shape opinions and say to fans, to people who may not be focused on this, that gays are just like you and me.”

In the past week, Ayanbadejo has been contacted by supporters in Brazil, Norway, England, Australia, Colombia and Ireland. He has also been overwhelmed by the support of his Ravens teammates and other N.F.L. players. “I’d say the majority of players are siding with me, that all people have a right to live and love and be happy,” Ayanbadejo said in a telephone interview. “That’s really amazing. I’m very happy to see the tides changing in the positive.”