Cambridge, Massachusetts (CNN) As Elizabeth Warren's candidacy for president caught fire this summer, so did images of her seemingly endless energy: running on to the stage at campaign events; punching the air when she speaks; working the photo line for hours after rallies.

In the evenings, Warren keeps moving, often doing laps around the hotel grounds or pacing in the lobby. But she does it with a different kind of intensity -- this is when she is starting to unwind, talking on the phone with her husband, Bruce Mann.

A professor at Harvard Law School specializing in legal history and property law, Mann is unquestionably the quieter half of the couple. Friends, colleagues and campaign aides say Mann has never been one to seek the public spotlight. But as Warren climbs in the polls, there may be no escaping it.

On a recent Friday morning, Mann and Bailey, the couple's rambunctious 16-month-old golden retriever, answered the side door of their Cambridge home, letting CNN reporters inside for the couple's first joint interview of the campaign. Mann's left hand was in a hard cast -- he had recently broken a bone while trying to break up a fight between Bailey and a neighbor's dog. ("Bailey got jumped, let's be clear," Warren would later insist -- she's never known Mann to get caught up in a scuffle. "Bruce went to Bailey's rescue.")

Asked about the couple's contrasting personalities, Mann, 69, responded with a smile: "It just works."

Seated next to her husband of almost 40 years in a white wicker chair in their back sunroom, Warren chimed in in agreement. "I don't want to be married to somebody like me. I want to be married to somebody like him."

If Warren is elected, Mann would play an unprecedented role as the first male presidential spouse. That role once seemed likely to go to Bill Clinton , a man thoroughly accustomed to the political stage. Mann would be a very different kind of first husband -- a longtime observer of politics, but far from a politician himself. A little more than four months out from the Iowa caucuses, Mann said he has not been closely involved in the ins and outs of the Warren campaign, and remains a mystery to most voters.

But those close to the couple say that Mann's influence on his wife's candidacy is not to be underestimated -- he has a unique ability to help his famously energetic wife decompress after long days of travel and campaigning, they said. "He brings a sense of calm to her more than anyone else could," said Nora Keefe, Warren's bodywoman.

Sen. Elizabeth Warren, husband Bruce Mann and dog Bailey.

"When you see the images of Elizabeth up in front of a crowd, waving her hands, just being part of the crowd, I can't quite imagine Bruce up there waving his hands," said Drew Faust, the former president of Harvard University who has been friends with the couple for years. "There's this enormous warmth between them. And he is obviously -- they are both obviously devoted to one another and take pride in their differences."

Warren noted that much of her life over the last year has been "different motel rooms every night, hotel rooms every night, different food, different people around, but I always know the last person I'll have a good conversation with, the last person I'll talk to before I go to sleep, is you."

Of those late-night phone calls, she said: "It's like letting all the pieces go."

That morning was looking like it could shape up to be what Warren describes as a "really good day": when she is home long enough to fit in two walks around Fresh Pond with Bailey and Mann, once early in the morning and again at night.

"There's really nothing better than a golden retriever puppy to create the illusion of normalcy," Mann joked.

"If you don't run and Democrats lose, you'll feel guilty"

In two wide-ranging interviews -- first with Mann and, later, the couple speaking together -- they discussed what has been anything but a normal year.

They couldn't pinpoint one moment when it became clear that Warren would run for president, something she had decided against doing four years ago. In the months leading up to the 2019 New Year, Warren had begun to quietly consult people whose advice she trusted, asking each of them for three reasons she shouldn't run, and three reasons she should.

"She saved me for last, and finally, she asked me for three reasons, pro and con. And I said, no, I'm not going to do it," Mann recalled. "I said, you're gonna run anyways. So just doesn't matter. Because if you don't run and Democrats lose, you'll feel guilty because then that means there'd be no one to fight for the people and the issues that you care about."

He was right. Warren would announce her exploratory campaign on New Year's Eve.

A registered Democrat and a self-described "political junkie" and "compulsive reader of newspapers," Mann said he has been exercising discipline to avoid being consumed by news about his wife's campaign. He is sparing in what he flags to Warren, who has said she doesn't follow the news about the election closely.

US Senator from Massachusetts (D) Elizabeth Warren is flanked her husband Bruce Mann as she is sworn in by Vice President Mike Pence.

Warren has also taken a similar approach to polling, repeatedly declining to engage questions from reporters about who's up and who's down. At one point in the joint interview, when Mann was asked why he believes his wife has been leading in recent polls, Warren leaned into her husband with a reminder: "And you remember, we don't do polls."

"That's right, we do not do polls," Mann said. But he offered up a theory on what has been attracting voters to his wife this year.

"She's always had just an extraordinary ability to explain complex issues, clearly, memorably," he said. "Watching people who hear her respond to her as she reaches them, as she helps them see how the issues touch their lives -- it's, I'm watching her teach on a larger stage."

"I just fell for her from 25 yards out"

The couple's first meeting in the summer of 1979 was, as Mann describes, "improbable." He and Warren were both 29 and new to teaching, and had traveled to Key Biscayne, Florida, to attend an economics and law conference.

He spotted Warren, who had recently separated from her first husband, Jim Warren, across the lawn at an opening reception. "Even from that distance, I was just drawn to her," he said. "She was so just lively, so animated, so engaged. And I just fell for her from 25 yards out before even meeting her."

Admittedly, it wasn't quite love at first sight for Warren.

"That was a Sunday, late afternoon," she mused of their first meeting. "I wasn't completely in love with him until sometime mid-morning on Monday."

What sealed the deal for Warren: "It was on Monday when I actually saw him in shorts. And good-looking legs. That's when I was all in."

"She completely objectified me," Mann responded with a grin.

If there was an immediate physical attraction, the pair also bonded over their similar upbringings.

Warren was born in Oklahoma City, the baby of four. As she has told voters on the campaign trail this year, Warren vividly remembers watching her mother walk out of the house one day to look for a job after her father suffered a heart attack. Mann's parents didn't have much money, either. "They stretched and stretched and mortgaged to the hilt to buy the cheapest house in the town with one of the best public school systems," he said.

Within months of their first meeting in Florida, Warren visited Mann at the University of Connecticut, where he was teaching at the time. She sat in on one of his classes, and after all of the students had left, Mann recalled asking her: "What'd you think?'"

"And she just said, 'What can I say? Will you marry me?' And I said, 'OK.' That is a direct quote, I remember every word."

The couple juggled living in different cities long after they were married. Warren would continue teaching in Texas, before eventually getting hired at the University of Pennsylvania, where Mann also taught for almost 20 years. But when Warren landed a full-time teaching position at Harvard University in the 1990s, it would be years before Mann would also get a professorship at the school.

They leaned on Warren's aunt, "Aunt Bee," to help raise Warren's two children from her first marriage, Amelia and Alex. In campaign speeches, Warren credits her aunt, after whom she is named, for changing the course of her life. She credits Aunt Bee, who lived with the family for 16 years, for having allowed her to continue teaching.

"Oh, she'd be so proud. She loved Elizabeth dearly," Mann said of Aunt Bee, who died in 1999. If she were still alive and observing Warren's 2020 campaign, Mann said, "Her first response would probably be: 'How can I help?'"

"You just jump into the deep end and you swim"

Something else that seemed improbable to Mann in 1979 was that politics would be in the couple's future.

Warren was a Republican when they first met. She wouldn't change her party registration to Democrat until 1996. "However conservative she might've been at the time, it was not particularly apparent and we really didn't discuss politics," Mann said.

But by 2011, Warren had made a name for herself in Washington, overseeing the Trouble Assets Relief Program after the financial crisis and conceiving of the Consumer Financial Protection Bureau under President Barack Obama. That September, she mounted her first political campaign against Massachusetts Republican Sen. Scott Brown.

Sen. Elizabeth Warren onstage which her husband Bruce Mann and dog Bailey.

It was during this closely watched Senate race that Warren first came under fire for her past claims to Native American heritage. She would defeat Brown, handing the Democrats a major pick-up in the Senate, but the criticism of how Warren handled her family history lingered. Her campaign's decision last year to release the results of a DNA test, which showed distant Native American ancestry, was widely panned.

For Mann, who was close to Warren's extended family in Oklahoma, these criticisms were particularly painful.

"I knew everyone in her family, loved her family, knew all the stories that they had grown up with," Mann said. "Because it was an attack on her family, it was one that was sort of probably the least pleasant of the attacks she's endured."

As for the possibility that Warren would be up against Trump if she were to win the Democratic nomination, Mann was matter of fact.

"I'm not sure if anyone -- how anyone trains for it," he said. "I mean for all of this, you just jump into the deep end and you swim."

The couple also insisted that they do not talk about what life could be like at the White House. "It's a bit early for that," Mann said. In the classroom, Mann said he never mentions his wife's name or the campaign, a boundary that his students have been respectful of.

"They observe that separation. It's probably killing them, but they're very good," he said.

Mann has not done any interviews this year, with the exception of a brief encounter with reporters outside of their Cambridge home on New Year's Eve, hours after Warren announced her exploratory campaign. Prompted for a comment, Mann had said that day: "We've been married a long time and it's always been an adventure. So this is just another one."

Asked how that adventure was going, Mann told CNN: "Extraordinarily well."

"Certainly back then, I had no idea what it would look like -- only that we would do it," he said. "Every part of it remains an adventure. So I stand by that statement."