NEW YORK (NYTIMES) - Bill de Blasio, the Democratic mayor of New York City, announced Thursday (May 16) that he was running for president, seeking to show that his brand of urban progressive leadership can be a model for the rest of the nation.

It will be a steep challenge: He becomes the 23rd Democrat to enter the presidential race, and he does so against the counsel of many of his trusted advisers, and in the face of two centuries of history.

No sitting mayor has been elected to the presidency, and if Mr de Blasio is to be the first, he must overcome daunting deficits in polls and fundraising.

His announcement, in a three-minute video titled "Working People First," comes after months of groundwork that has included visits to early presidential primary states, a fundraiser in Boston and a circus-like news conference this week in the lobby of Trump Tower.

In pre-campaign stops in Iowa, South Carolina and New Hampshire, Mr de Blasio, 57, has said that the country is witnessing "the dawning of a new progressive era" and said in interviews that his leadership in New York should be seen as a model for how "you can make profound progressive change and make it quickly."

He is fond of citing his "pre-K for all" programme as a prime example; it was one of de Blasio's earliest initiatives, and it remains his largest success. He also highlights various measures to attempt to reduce income inequality in the city and to end the policing practice of stop-question-and-frisk, which a federal judge ruled discriminated against black and Latino men.

"All of the things I've told you, they're happening," the mayor said last month at the National Action Network's annual convention. "They're not words, they're deeds. They're happening here. They can happen all over this country."

Mr de Blasio plans to fly to Iowa on Thursday night. He will campaign there Friday and then visit South Carolina for campaign stops Saturday and Sunday.

Mr de Blasio often says that he has a "story to tell" about New York's accomplishments, but his own narrative is also compelling.

He was born Warren Wilhelm Jr to a German-American father and an Italian-American mother; his father, a veteran who struggled with alcoholism, later killed himself. His relationship with his father was strained, and Mr de Blasio eventually took his mother's last name.

Raised in Massachusetts, Mr de Blasio attended New York University and became a leftist activist who admired Nicaragua's ruling Sandinista party. He later ran campaigns for Hillary Clinton and Charles B. Rangel, and then ran for office himself, winning elections to become a New York City councilman, public advocate and mayor.

He is married to Chirlane McCray, who has spearheaded ThriveNYC, the city's mental health initiative; they have two children and their bi-racial family's prominence, particularly their son Dante's Afro, played a large role in his 2013 campaign for mayor.

Some of Mr de Blasio's colleagues have scoffed at the idea of him becoming president and have urged him to abandon his exploration of occupying the White House and instead focus on a bevy of nagging issues in New York City, such as crumbling public housing, high levels of homelessness and problem-plagued subways. Mr de Blasio said that many of the answers for what ails the city actually lie 200 miles beyond its borders in the nation's capital.

"I am concerned that I think right now our federal government is not helping New York City in a whole host of ways, and we're being hurt all the time by bad policies in Washington," Mr de Blasio said at a news conference last month. He cited the lack of a national infrastructure plan and fractured health care policies. "So real changes are needed in our country," he said. "If they don't happen, New York City continues to suffer."

The mayor will have to make up a huge fundraising disadvantage as he builds out a campaign staff and close a seemingly insurmountable gap in polls. In a Monmouth University poll last month, Mr de Blasio had a net favourability of zero: 24 per cent like him, 24 per cent do not like him. Senator Bernie Sanders of Vermont is the only candidate with a higher unfavourability number, 26 per cent, but his favourability rate was 67 per cent.

Mr de Blasio seemed undaunted, saying that if he had listened to the polls, he would have never run for mayor or public advocate.

Mr de Blasio joins a crowded field that already includes two other current mayors: Pete Buttigieg of South Bend, Indiana, and Wayne Messam of Miramar, Florida.