You’d be hard pressed to find a political consultant who couldn’t perform a convincing swoon for the candidate he or she is promoting. But when Josh Isay talks about Christine Quinn and the chance of her becoming the next mayor of New York, you see something else, something more. His eyes actually mist.

It’s a particular thought that gets to him: Quinn and her wife — two women — moving into Gracie Mansion together. It’s the symbolism of that, and what it would have meant to a man he loved deeply, a man whose painful, remarkable journey through life still makes him ache. Josh’s father, Richard Isay, was gay.

Josh wavered when I approached him for an interview about that. The Quinn campaign for the most part hasn’t blared or bragged that she would be New York’s first openly gay mayor and its first female one: neither a reason to vote for her.

But as the race tightens and the Democratic primary nears, the campaign seems to be letting a little more emotion into the mix. Over recent days, Quinn’s wife, Kim M. Catullo, did a series of interviews with journalists.

And Josh can’t pretend that the precedent of Quinn’s possible election isn’t always in his head.

“Her winning would be such an incredible way to honor my father’s memory,” he said when we sat down last week.

Although he’s worked hard in the past for Chuck Schumer, Michael Bloomberg and other politicians, it wasn’t quite the same.

“He never cared about anything the way he cares about this,” Dave Isay, his older brother, told me. “It’s visceral. It’s personal.”Richard Isay died last year at age 77. He was a renowned Manhattan psychiatrist and psychoanalyst, hugely influential in getting his peers to see homosexuality as normal.

But that public fight echoed a private one, over his own identity. It took several tortured decades for him to accept his own sexual orientation.

He tried to change it with therapy. He tried to bury it within his marriage to Josh’s mother, Jane. This was in the 1950s, ‘60s and ‘70s, an era of secrets and lies for most men like him.

In 1980, after meeting the man who would be his romantic partner to the end, he finally told his wife who he really was. Dave was then 14 and Josh 10, and partly for their sake, the couple stayed together, in a fashion.

Josh remembers that his father was always away two nights a week, supposedly for work. He didn’t learn the true reason until he was 17, and initially kept it to himself. “I was embarrassed,” he told me, “and I felt guilty about being embarrassed. I still do.”His parents ended their marriage shortly after that, and Josh learned more about his father’s self-deception and sorrow, which his father went on to describe publicly, becoming a prominent gay-rights advocate, appearing on “Oprah” and writing a 1996 book, “Becoming Gay.”In it Richard Isay recounts his anxiety-laden attempts to summon sexual desire for a woman and how “lonely, depressed, and, at times, desperate” he was. He even tells of a 1974 encounter at a highway rest stop with an undercover cop who arrested but then took pity on him, a Yale instructor and family man, and agreed not to press charges.

Every parent’s stamp on a child is big and lasting. Richard Isay’s on Josh has specific contours. It has made him more conscious of, and angry about, bigotry and repression, whose wages were paid by his mother as well as his father.

“I wish both of them could have lived the most full lives possible,” Josh, 43, said.

He worked on the campaign for same-sex marriage in New York. And less than a month after it became legal in 2011, Richard Isay was wedded to Gordon Harrell, the man he’d fallen in love with three decades earlier. The ceremony was in Josh’s apartment. The elder of Josh’s two children, Benji, then 7, was the best man.

Josh likes to imagine a society in which most kids had Benji’s exposure and perspective. He likes to think that the example of two women in Gracie Mansion would hasten its dawn.

He told me a story. He recently asked Benji, now 9, about his day, and Benji mentioned a colorfully attired man on the subway who was “dressed gay,” in Benji’s words.

Josh admonished him for his language, at which point Benji started bawling. He explained to his father that he hadn’t meant to be mean; he’d heard gay men at times talk that way about one another.

“There was zero understanding that calling someone gay was an insult,” Josh said. He couldn’t have sounded prouder if he’d been telling me that Benji had won the school spelling bee.