(RNS) A bipartisan coalition of 80 U.S. mayors on Friday (Jan. 20) launched a “Freedom to Marry” campaign to build public support for giving same-sex couples the right to marry under U.S. and state laws.

“It is not about what you want to believe or what you think is right or wrong,” said New York Mayor Michael Bloomberg, who presided at the same-sex ceremony of two staffers last July, at a Washington news conference.

“It is also not about what organized religion should or should not do. This is a civil rights issue.”

Bloomberg and other mayors cited moral and monetary reasons for why same-sex couples should be permitted to marry. After New York legalized gay marriage last summer, Bloomberg said hotels, caterers and banquet halls all benefited.

“For me, the question is not if marriage equality will come to all 50 states; the only question is when,” said Bloomberg, an independent. “I believe that day will come sooner than most people think.”

Six states and the District of Columbia currently permit gay marriages.

Mayor Jerry Sanders of San Diego said he was an example of how minds can change on the issue.

“Each year, more and more Americans are going through the same evolution that I did,” said Sanders, a Republican, who changed his position after learning that his daughter was a lesbian. “I can assure you that there's nothing to fear.”

Houston Mayor Annise Parker, a lesbian mother, also brought a personal perspective to the issue.

“By telling my family and my kids that they are not second-class Americans,” said Parker, a Democrat, “we can build a stronger America and a stronger future for all of us.”