Late last year, when Pete Buttigieg first began reaching out to potential donors in advance of his long-shot presidential bid, one of the people he consulted was Howard Dean. The former Vermont governor had also mounted a dark-horse bid for the White House, in 2003, back when Buttigieg was downloading Phish MP3s from LimeWire in the Harvard residence halls. Dean is remembered by most political observers as surfing a massive grassroots wave from nowhere thanks to his early and fervent opposition to the Iraq war, an argument that flooded him with small online donations at a time when the Internet was only just beginning to de-stabilize American politics.

But Dean reminded Buttigieg of something lost in popular memory: his early support for civil unions. In April 2000, Dean had signed the nation’s first law allowing same-sex civil unions, then a groundbreaking step in the nation’s slow march to marriage equality. At the time, the law was so controversial, so aberrant to the American mainstream, that Dean had to wear a bulletproof vest at times in public. But as Dean began to assemble a presidential campaign, his support for civil unions was a door opener. Running for re-election in Vermont that fall, Dean was the toast of the L.G.B.T. fund-raising circuit, appearing at several events hosted by the Human Rights Campaign. He later appeared on the cover of The Advocate in a very hetero-looking fleece half-zip under the headline “A Civil Unions President?” His connections in the gay community would become foundational as he began to raise money and put together an organization.

“I’m not sure Howard Dean fully appreciated this at the beginning, but civil unions was kind of a made-up artifice,” said Elizabeth Birch, who was then the executive director of the Human Rights Campaign. “It had no legal meaning. It was made-up legal creature that had no history in the country. But because Dean had supported at least what would be the equivalent of a domestic partnership, that was the biggest step to date. He went on our dinner circuit. And the H.R.C. had really grown into a formidable organization. We bought talent from Silicon Valley and it became a real force. Dean was able to tap into that, appear at a number of dinners, and really impress people. He was intelligent. He was a truth-teller.”

Dean’s early ask to L.G.B.T. donors in 2002, as he launched his presidential exploratory committee, was similar to Buttigieg’s last year as he ramped up his potential bid: I might not be your first choice, but I’d appreciate some of your support as I try this. His rapport with the gay and lesbian political community was critical. It became the building block upon which he would capitalize as he broke into the mainstream. Big L.G.B.T. donors had fancier names to support, like John Kerry, Dick Gephardt, and John Edwards, but they also tossed some friendly extra cash Dean’s way because they respected his bravery on civil unions. “I showed up on the campaign early and almost everyone there was there because of civil unions,” said Nicco Mele, the “Web master” of the Dean campaign who now teaches at Harvard. “Almost all of the early money was around the civil-unions issue from the gay community.” Dean lost that 2004 campaign, but he raised more money than any candidate in the Democratic primary.

Seventeen years later, so much has changed. Other states began to recognize civil unions, then same-sex marriage. In 2012, President Barack Obama became the first sitting president to openly support marriage equality. The Supreme Court in 2015 made same-sex marriage the law of the land after a five-four ruling in Obergefell v. Hodges. And today, an openly gay man is not only running for president, but has leapt to third place in the Democratic primary polls behind internationally famous candidates Bernie Sanders and Joe Biden. Buttiegieg’s sexual orientation is not a central theme of his campaign message, but it doesn’t need to be for prominent L.G.B.T. donors who have grown accustomed to supporting candidates who are friendly on their issues, but never one their own.