The nation's largest lesbian, gay, bisexual and transgender civil rights organization announced Wednesday it is endorsing Gov. Mark Dayton for re-election.

The Human Rights Campaign said Dayton has "a stellar record" on LGBT equality. The group made the endorsement on the one-year anniversary of Dayton singing a measure to legalize same-sex marriage in Minnesota.

"Governor Dayton led Minnesota into its full embrace of LGBT equality," said Marty Rouse, an HRC spokesman. "He took pro-equality stances before they were politically safe and has been a champion of all people, working families and LGBT Minnesotans alike."

"I am honored to receive the Human Rights Campaign's endorsement," Dayton said in a statement. "HRC's good work in Minnesota was vital in defeating the attempt to put discrimination into Minnesota's Constitution by banning marriage equality in 2012, and equally important in our great victory last year, when we ensured that every Minnesotan has the right to marry the person he or she loves."

The Human Rights Campaign has emerged as a powerful and well-financed organization working to legalize same-sex marriage across the country. It is also using its vast fundraising resources to defend elected officials who have backed their cause.

The group noted that Dayton supported same-sex marriage before he was elected. When he served in the U.S. Senate, he voted against the Federal Marriage Amendment. He also co-sponsored a measure that would have extended benefits eligibility to the domestic partners of civilian federal employees.