The LGBTQ Victory Fund on Friday endorsed Pete Buttigieg, the openly gay mayor of South Bend, Indiana, for president.

The endorsement came a day after Buttigieg became the first openly gay presidential candidate to participate in a presidential debate and the 50th anniversary of the Stonewall riots, which is widely credited with sparking the modern LGBT rights movement.

“Tonight, we are officially endorsing Mayor #PeteButtigieg's campaign for President of the United States,” the group said in a tweet. “Mayor Pete has the experience, record of service, and vision that is required to not only lead this nation – but also to defeat Donald Trump at the ballot box.”

A formal endorsement was made at a campaign event on Friday in New York. At the event, Buttigieg was joined by his husband Chasten Buttigieg.

“I'm honored to have your support,” Buttigieg tweeted in response. “My candidacy is possible only because of the hard work and sacrifice of LGBTQ activists who stood up for change 50 years ago today, and the leaders who continue that fight for equality at organizations like @VictoryFund #Stonewall50.”

According to USA Today, the Victory Fund's board unanimously voted several weeks ago to endorse Buttigieg for president. However, the group has been supportive of his campaign, hosting a fundraising event in April.

Victory Fund is the largest political action committee (PAC) committed to electing LGBT politicians to office. However, it only endorses candidates which it believes are electable. In 2012, the group neglected to endorse the campaign of Republican Fred Karger, the nation's first openly gay presidential candidate.

Karger, who appeared on 6 state ballots in 2012, has said to On Top Magazine and other outlets that he fears his historic run is being erased. “I've got a very sick feeling that my candidacy is attempting to be erased,” he said in an email in response to the media attention Buttigieg has received without noting his contributions.