Trailing a month ago, Bill de Blasio is now the candidate to beat in NYC's mayoral race

NEW YORK — Bill de Blasio bounded into a campaign rally in the shadow of a Brooklyn courthouse trying hard to act like it was any other day on the mayoral campaign trail.

But it wasn’t. Earlier this week, the well regarded Quinnipiac University poll found that de Blasio, the city’s public advocate, had opened a surprise lead in the city's Democratic mayoral primary — besting City Council Speaker Christine Quinn, who until recently had been widely considered the heir apparent to outgoing Mayor Michael Bloomberg.

“There is absolutely positively nothing different,” de Blasio insisted, when asked about the poll suggesting he’s the new front-runner in the race. “It doesn’t matter if the polls are good or bad. My vision for the future is the same in every way.”

But it was definitely different for the 52-year-old Brooklyn resident, whose campaign hadn't received much attention until recently. While his audience of voters at the courthouse was sparse, he spoke to a crowd of reporters that was noticeably larger than at previous events. And suddenly, staffers were fielding requests from a host of national news organizations — including MSNBC, where he appeared twice on Wednesday.

It was a major publicity boost for a candidate who just a month ago was trailing in a distant fourth place, behind better-known contenders, including former Rep. Anthony Weiner and former Comptroller Bill Thompson, who narrowly lost to Bloomberg in the 2009 general election.

Inside his campaign, aides seemed to be caught off guard by de Blasio’s sudden rise in the polls — with one insider admitting that while they had expected de Blasio’s fortunes to rise, even they weren’t sure if the latest poll signaled a true surge in support.

“He’s been running as an underdog, and we are going to continue to run as the underdog in the race, focusing on the issues and vision for the city that he believes are important,” the de Blasio aide, who declined to be named discussing campaign strategy, said.

Until recently, de Blasio had largely been known as the gangly tall guy in the campaign. At 6-foot-5, he towers over his rivals — and virtually everyone else in New York, the exception possibly being players from the Knicks.

He has also been known for what the New York Times deemed his “modern family.” His wife, Chirlane McCray, is black and has been open about the fact that she was a lesbian before she met her husband. McCray and the couple's two teenage kids — Chiara, 18, and Dante, 15 — have been mainstays on the campaign trail, helping de Blasio project the image of a family man in a campaign largely overshadowed by Weiner's sexting escapades. Bloomberg, a divorced father of two, is a bachelor.

But de Blasio's family has also been an important symbolic part of his campaign as he seeks to appeal to an increasingly multicultural city that has been divided over Bloomberg’s tenure.

Last week, Dante de Blasio appeared in a campaign ad criticizing Bloomberg’s embrace of the controversial stop-and-frisk measure that allowed police officers to randomly search people. The measure was thrown out earlier this week by a federal judge, who argued that it violated the rights of minority residents in New York who the court said had been unfairly targeted. Bloomberg has vowed to find a way to reinstate it.

In the campaign ad, Dante de Blasio speaks directly into the camera and said his father is the “only one who will end an era of stop-and-frisk that unfairly targets people of color.”

“He’s the only Democrat with the guts to really break from the Bloomberg years,” Dante de Blasio says in the spot, adding that his father would be “a mayor for every New Yorker, no matter where they live or what they look like.”

De Blasio first made his name in New York City politics as an aide to the city's first black mayor, David Dinkins. During the President Bill Clinton’s administration, he was appointed as a regional director for the Department of Housing and Urban Development. He made his debut on the national political scene in 2000 managing Hillary Clinton’s New York Senate race.

De Blasio was elected to New York’s City Council the following year, representing parts of South Brooklyn. He was elected public advocate in 2009 — a citywide watchdog role whose actual function is somewhat murky to most New Yorkers.

In his capacity as public advocate, de Blasio has made news in recent weeks trying to stop several neighborhood hospitals from being closed — even getting arrested during a protest outside one medical facility last month.

An overarching theme of de Blasio’s mayoral campaign has been a focus on inequality in New York. He pledges if elected to invest in helping poor and middle class residents who he says have been ignored by Bloomberg, a multibillionaire often criticized for lacking a common touch. He has frequently described New York as a “tale of two cities, a place where City Hall has too often catered to the elite rather than the needs of everyday New Yorkers.”

Eyeing the shifting polls, Quinn and other rivals are already targeting de Blasio, criticizing what they say is a thin legislative record and suggesting he has not been as passionate about themes of inequality in the past. They've pointed out he once opposed a proposed tax increase aimed at rich Wall Street financiers.

They have also criticized de Blasio's proposal to raise taxes on New Yorkers earning more than $500,000 a year to help pay for universal prekindergarten, saying it could drive away some of the city’s biggest taxpayers.

But de Blasio’s progressive stance has won him some major endorsements — including from liberal icons like onetime Democratic presidential candidate Howard Dean and megadonor George Soros. He’s also campaigned in recent weeks with “Sex and the City” actress Cynthia Nixon and singer Harry Belafonte. On Sunday, he’ll campaign with actress Susan Sarandon at her ping pong bar in Manhattan.

But a source close to de Blasio insists that his rise in the polls or big endorsements won’t change how the mayoral hopeful operates on the campaign trail. He’ll keep running like he is behind until the Sept. 10 primary.

“We have some energy behind us, but we are not taking anything for granted at all,” the campaign source, who declined to be named, said.

And that’s how de Blasio has operated on the campaign trail in the past 48 hours — though he admitted he had celebrated a little.

“My son insisted that we go to Cheeburger Cheeburger,” de Blasio told the New York Daily News, referring to the ‘50s-style burger chain, which has an outpost near his home in Brooklyn. “Other than that, it was business as usual.”

William Holt contributed to this report.