Mayor Julian Castro at San Antonio’s gay Pride in 2009 (via the San Antonio Express-News).

San Antonio Mayor Julian Castro, who keynotes the Democratic National Convention tonight, has been a friend to the LGBT community since he was elected in 2009.

Soon after he was elected, Castro became the first mayor of that city to serve as grand marshal of the Pride Parade.

When a Christian radio station talk show host organized a protest of Castro’s participation in Pride, Castro responded firmly about where he stood.

“To equate lesbians and gays with something immoral is just wrong,” he said.

Earlier this year, Castro signed the Freedom to Marry Pledge.

“Today I proudly joined the mayors of Houston, Austin, New York, Chicago, Boston, Los Angeles and more than 60 other American mayors of cities big and small in support of the ‘Mayors for the Freedom to Marry’ petition for same-sex marriage equality,” Castro wrote on his Facebook page the day he signed the pledge.

Last September, Castro spearheaded a push to offer domestic partner benefits in his city, which passed the City Council on a 8-3 vote. The item was originally part of the general city budget but was pulled out as a separate item and council members were able to comment on it.

“This is not a new issue — this should have be done some time ago,” Castro said, speaking in support of DP benefits.

Speaking to Stonewall Democrats in 2009, Castro told the group there are no second-class citizens in San Antonio.

When he speaks tonight, Castro will become the first Hispanic keynote speaker at a national Democratic or Republican convention. His 15-minute speech is being compared to President Barack Obama’s speech at the 2004 Democratic Convention that began his rise to the White House even before he was elected to the Senate that November.

In his keynote address, Castro is expected to talk about striving for the American Dream. Earlier in the evening, delegates are expected to approve a platform with a number of pro-LGBT planks, including marriage equality. Castro will be speaking to a crowd that includes more LGBT delegates than have ever attended a Democratic convention. There was no advance word about whether Castro would include LGBT issues in his speech, which is set for 9 p.m. Central time.