NEW YORK (AP) — Bill de Blasio was sworn in as the 109th mayor of New York City on Wednesday, becoming the first Democrat to occupy City Hall in more than two decades while vowing to pursue a sweeping liberal agenda for the nation's largest city.

De Blasio took the oath of office moments after midnight in front of his modest Brooklyn home. His inauguration was to be celebrated on a far grander scale at noon on the steps of City Hall when he takes the oath again, administered by former President Bill Clinton.

The new mayor was elected two months ago by a record margin on the promise of being a sharp break from Michael Bloomberg. Bloomberg leaves office after 12 years that reshaped New York, making it one of the nation's safest and most prosperous big cities but also one that has become increasingly stratified between the very rich and the working class.

De Blasio, 52, was joined in the first minutes of 2014 by his wife, Chirlane McCray, and their two teenage children, a close-knit interracial family who played a central role in his campaign and to some are a further symbol of a new era after the data-driven, largely impersonal Bloomberg years.

"To everyone, this is the beginning of a road we will travel together," de Blasio said after taking the oath administered by state Attorney General Eric Schneiderman.

Dozens of staffers and supporters — including actor Steve Buscemi, former Vermont Gov. Howard Dean and U.S. Ambassador to South Africa Patrick Gaspard — braved the frigid temperatures to crowd 11th Street, once an unassuming block in the Park Slope neighborhood, now the center of the city's political power.

De Blasio waved to the crowd after taking the oath and hugged his wife and children, each of whom dressed for the festive event: Chiara, 19, was wearing a party hat while Dante, 16, was sporting jeans.

"I want to thank you for having brought us to this moment," de Blasio said. "Many great things ahead for all of us."

Standing in the same spot where he launched his then-longshot mayoral bid in January, the new mayor signed the oath and paid the requisite $9 fee to the city clerk. He then thanked the crowd, saying he'd "see them tomorrow" before heading back inside the brightly lit home.

The inauguration portended to be a joyous day for city Democrats, who outnumber Republicans in the city by a margin 6-to-1 but have been shut out of power since David Dinkins left office on New Year's Eve in 1993.

The party's ascension was underscored by the presence of Clinton and his wife, former Secretary of State Hillary Clinton, who is mulling a presidential run in 2016.

Both Clintons have ties to de Blasio: the new mayor worked for the former president's administration in the Department of Housing and Urban Development and helped manage Hillary Clinton's successful 2000 Senate campaign. De Blasio and his wife are also frequently compared to the Clintons since McCray has long been considered the new mayor's most powerful, if informal, adviser.

De Blasio, an unabashed progressive who touts his Brooklyn roots, takes office at a crucial juncture for the city of 8.4 million people.

As New York sets record lows for crime and highs for tourism, and as the nearly completed One World Trade Center rises above the Manhattan skyline, symbolizing the city's comeback from the Sept. 11, 2001 terror attacks, many New Yorkers have felt left behind during the city's renaissance.

De Blasio reached out to those he contended were left behind by the often Manhattan-centric Bloomberg administration, and he called for a tax increase on the wealthy to pay for universal pre-kindergarten.

He also pledged to improve economic opportunities in minority and working-class neighborhoods and decried alleged abuses under the police department's stop-and-frisk policy. He and his new police commissioner, William Bratton, have pledged to moderate the use of the tactic, which supporters say drives down crime but critics claim unfairly singles out blacks and Hispanics.

Bratton was also sworn in just after midnight, receiving the oath of office at police headquarters.