The reason Gus Christensen looks like an investment banker is that he was one until four months ago. A handshake reveals a shirt monogram over the wrist, an Omega watch and lapis cuff links he got on a JPMorgan Chase & Co. trip to Chile.

One clue to his new line of work was the Vineyard Vines tie with donkeys he wore to the Yale Club on Feb. 27. Another was his name on the program for that night’s annual Lenox Hill Democratic Club dinner as president and benefactor.

“Reactionary forces are strong,” he told his neighbors from New York’s affluent Upper East Side, their forks and knives clinking as they ate mushroom tart. “But the progressive side is stronger. And both time and right are on our side.”

Christensen didn’t quit banking just to head a local political club. With investors Tom Perkins and Ken Langone comparing the battle against inequality to Nazism, the language they despise is fueling the 42-year-old’s nascent campaign for New York State Assembly, a job that pays $79,500 a year. Money from working two decades on Wall Street will help fund his mutiny against some of its treasured principles.

In his dinner speech, Christensen’s voice lurched and swelled to find the rhythm of the pulpit. He preached stronger rights for workers and women, tougher regulation, cheaper housing and “progress on inequality itself.”

Ayn Rand

Christensen, once a JPMorgan derivatives trader and a Goldman Sachs Group Inc. banker who worked on casino deals, mocked the vanity of Ayn Rand novels financiers adore, put his minimum-wage goal at $15 an hour and praised Massachusetts Senator Elizabeth Warren’s efforts to curb the banks that once paid him.

“I’ve come out of that with a slightly different, or maybe radically different, point of view than a lot of other members of the financial community,” he said in an interview last month. “I may be an idealist whose hopes and dreams are crashed on the rocks of reality in short order.”

Christensen was drawn away from Wall Street slowly. He was bothered by President George W. Bush’s tax cuts for the rich, disheartened by bankers demanding soft regulation and happier volunteering for a friend’s 2012 bid for Congress than he’d been in his day job, he said.

That friend lost to an incumbent, a fate Christensen will avoid. Democrat Micah Kellner, who appealed an Assembly ethics committee decision that he violated its sexual harassment policy, isn’t running for re-election in November. Iraq veteran David Menegon and community-board member Ed Hartzog, both Democrats, are among candidates vying to replace him.

Hurt Feelings

Christensen has faced criticism even before officially declaring his candidacy to represent Manhattan’s 76th Assembly district, which stretches from 61st to 92nd streets east of Third Avenue and includes Roosevelt Island. He spent more than $2,600 on Lenox Hill dues for about 150 friends and colleagues to help him win the club’s presidency, the Daily News reported in January.

The explanation he gave in the interview last month about why he paid for friends to join the club, and how he feels after winning, had the long zigzag of testimony some of his former Wall Street colleagues have delivered in Washington.

“I didn’t come in off the street and, quote, buy this club,” he said at first, describing the support older members showed him. “Look, I regret how it played out, I regret how some people’s feelings were hurt,” he added. Then he described paying dues for some people to counter “moves that the other side had made to control the nominating procedures.”

Secret Republican

Sounding like a defensive banker is one thing; looking like a secret Republican is another. An audience member at a Stonewall Democratic Club meet-the-candidates talk last month asked him if he’d once been registered to vote for the rival party. Christensen said he didn’t believe he had.

“I fumbled the answer,” he said a week after the session, acknowledging that Board of Elections records showed he was registered as a Republican until early 2007.

He said he had forgotten about the registration because politics once mattered much less to him than work. All his donations have gone to Democrats, according to Federal Election Commission records. Still, he once saw himself as a fiscal conservative.

“I believed much more than I do now in the power, in the neutral goodness, of unfettered free markets,” he said. Loosened financial regulation had “real negative consequences that I certainly didn’t foresee when I was a young trader.”

Fashion Model

Christensen grew up in Brooklyn’s Park Slope, the son of two tax lawyers. His mother worked for Citibank, and his father represented philanthropist and socialite Brooke Astor. The younger Christensen went to Saint Ann’s School in Brooklyn Heights, with a year at New Hampshire’s Phillips Exeter Academy. After graduating from Yale University in 1994, he joined JPMorgan’s training program.

He left the bank in 2000, the year he was plucked for a photo shoot during a ski trip to Badrutt’s Palace in St. Moritz, Switzerland. He donned Dunhill ski wear for a fashion shoot in British GQ that year, according to a New York Observer story.

“Some people just have a classic look,” a fashion editor said about him then. “There’s something timeless about him.”

Casino Banker

Christensen received a master’s in business administration from the Wharton School of the University of Pennsylvania in 2003 and took a job at Goldman Sachs, where he helped advise Colony Capital LLC on casino purchases.

“When you get to see the casinos in Indiana and the casinos in Mississippi, they’re not the great engines of local economic redevelopment that they were sold as,” Christensen said. “Did I have moral misgivings about it? I think that’s kind of a strong word.”

He left two years later for Evercore Partners Inc., the boutique investment bank where he worked on mergers and acquisitions as a managing director. His clients included restaurant chain O’Charley’s Inc. and General Motors Co., the carmaker that filed for bankruptcy in 2009. A Justice Department trustee called the fees Evercore wanted “staggering.”

When Christensen worked on Yale friend Julian Schreibman’s campaign for Congress in 2012, he found himself enjoying the door-to-door canvassing and strategy more than work.

“For the first time in my life, since I stopped wanting to be an astronaut at the age of 15 or 16, I saw something else that I wanted to do more than being a banker,” he said.

‘Not Angry’

December was his last month on Wall Street. In mid-January he disclosed contributions of $145,000 on top of a $250,000 loan he made to his nascent campaign. By the end of March his full name, Gustavus Adolphus Henry Christensen IV, was grist for a fake Twitter feed whose icon is the mustachioed Monopoly man. The page calls him a “Gazillionaire banker.”

Even friends and colleagues who support his decision to give up banking have asked why he doesn’t want to go to Washington, or why he would want to become a politician.

“The laws that affect our day-to-day lives as New Yorkers most are laws that are written in Albany,” Christensen said.

He wants to fund programs for the poor by raising taxes on the rich, expand New York City Mayor Bill de Blasio’s push for universal prekindergarten to daycare, release thousands of nonviolent drug offenders from prison and boost the minimum wage and tax credits.

Venture capitalist Perkins and Home Depot Inc. co-founder Langone have apologized for causing offense. In a Bloomberg Television interview, Perkins added that he didn’t “regret the message at all” and said his watch was worth six Rolexes.

“I’m not angry at the barons of Wall Street,” Christensen said. “I don’t think that they’re collectively bad people who need to be punished. I am worried about the other side.”

‘Class Warfare’

His father, Henry Christensen III, stood near the doorway before the Yale Club dinner began.

“Certainly a number of my clients have said, ‘Gus, we’re delighted that you’re running,’” said the attorney, who advises families in Germany, Saudi Arabia and Switzerland as head of McDermott Will & Emery’s private-client practice in New York. “‘But why are you running as a Democrat?’”

The candidate’s wife, Courtney, a Sotheby’s art auctioneer, was standing there. They’d gotten married two weeks earlier. Her husband, she said, can understand both of the two cities de Blasio sees carved inside New York by widening inequality. Her father-in-law interrupted.

“All I’m saying,” he said, “is I don’t believe in class warfare.”