“I do solemnly swear that I will support the Constitution of the United States and the Constitution of the State of New York and that I will faithfully discharge the duties of the office of mayor of the city of New York according to the best of my ability, so help me God.”

When Bill de Blasio becomes mayor of New York City in twenty days he’ll recite a fifty-three-word oath in which, basically, he’ll promise to try his hardest to “faithfully discharge” his duties.

That doesn’t begin to describe what he’s signed up for. Not only is de Blasio moving from the low-profile, low-power post of public advocate—a kind of civic watchdog unique to New York and invisible to many of its citizens—to the enormous challenge of managing a $70 billion budget and occupying the most intimately scrutinized elected position in America. He has to do all that with the hopes of the progressive movement on his back.

That may sound naïve or hyperbolic, but that’s exactly what some people said about de Blasio’s “tale of two cities” critique, and they were wrong on the politics and on the policy.

Sure, if you’re so inclined, you can look at de Blasio’s résumé, with his stint at the side of the “New Democrat” Clintons and his nimble traipse through the politics of real estate development, and conclude that the mayor-elect is more shrewd strategist than true believer. But it doesn’t matter. Whether in his heart he’s Chance the Gardener or John Doe or the Real Deal, people want him to be the Real Deal, so that’s what he’ll be expected to be.

And if you detect New York chauvinism at work here, tell me, what progressive has a higher profile or a bigger mandate to reverse the erosion of American working-class living standards than the guy who’ll be mayor of a city with more poor residents than Philadelphia has people?

The scope of that potential and the size of the challenge confronting de Blasio are why The Nation and City Limits are teaming up to produce this blog on the transition now underway and the first 100 days of the mayoral term that begins January 1.

There is no question that New York City is at a crossroads. De Blasio’s surge this fall had even Crain’s, the leading business publication in town, acknowledging the reality of income inequality. The New York Times is this week giving unprecedented space to a series about a homeless girl navigating the city remade not so nicely by the Bloomberg era. A coalition of big foundations set up a tent in Tribeca to collect people hopes and suggestions for the first Democratic mayor since 1993.

“It feels like a New York transformed, for me,” says Andrew Friedman, co-executive director of the Center for Popular Democracy. “There’s a world of issues where it feels clear that the de Blasio administration is going to move with significant progressive policies in line with what we’ve been fighting for for years,” like paid sick leave, a municipal ID, stronger living wage provisions and more.

So, yeah, there’s an amazing array of hopes being pinned to de Blasio. But there are questions, too. At his Election Night victory party, people voiced doubts about the winner even as they cheered the size of his margin. Can he help the poor without neglecting the environment? Can he afford to empower black and Latino communities and gay and lesbian organizations? Can he deliver?

To some degree, John Lindsay—the last progressive who tried to transform New York—had it easier. He didn’t have to fret about being compared to John Lindsay. De Blasio will always have to worry that any hint New York is slipping back to the bad old days will cost him the support of the city’s center, and especially the editorial boards.

That’s why the mayor-elect made the decidedly conventional picks of Anthony Shorris, a veteran mover and shaker, as first deputy mayor and, for police commissioner, William Bratton, who in some ways pioneered the stop-and-frisk strategy that Ray Kelly put on steroids. Fact is, de Blasio needs a skilled manager in City Hall and someone with editorial-board credibility at One Police Plaza. “You’ve got to make people comfortable,” says one veteran pol. “He’s got to send business a signal and the elites a signal.”

Meanwhile, the city’s left is scarred by disappointment with Barack Obama, who never even pretended to be as progressive as de Blasio but still managed to accommodate away much of the hope invested in him.

Yet progressives seem to recognize that they need to give de Blasio some room to operate. Thus they largely acquiesced to the choice of the un-beloved Bratton. “I think people are very sympathetic to the fear that we are one crime spree away from putting the whole progressive agenda on the rocks,” says one advocate.

Of course, the looming question is, will something come up that has progressives pushing back? People recognize the unique political requirements for police commissioner and first deputy mayor. But when it comes to the schools chancellor, or the head of the city’s social services department, de Blasio will be under more pressure to name someone who excites people. There is already some concern that the mayor-elect has backed away from a promise to have an inclusive process for selecting the next schools chief.

City Limits has covered urban policy in New York since the fiscal crisis, always with an emphasis on stories that affected low-income neighborhoods, communities of color, the outer boroughs—sort of the “second city” in the Dickensian reference de Blasio made a slogan. Racially skewed policing, income inequality, affordable housing…those 2013 buzzwords have been our stock in trade since ’76. We can get deep into wonk territory on land-use policy or charter school co-locations, but we see all of it as part of the bigger endeavor to create a more just city.

That means we can be tough on officials, especially ones who speak the language of progress. (We’ve been tough on de Blasio at times: A profile I wrote in 2009 ticked off his spokesperson, who thought I took cheap shots. He was probably right.)

But now de Blasio is more than just another ambitious politician: He’s to be mayor of the greatest city in the world and the bearer of a multitude of hopes and expectations. We’ll be watching who he brings in to help him, the speeches he makes, the policies he changes and the moves the game’s other players—the press, advocates, labor, state pols and local leaders—make. The first 100 days is a crude convention, but it will give us a sense of who the 109th mayor of New York really is.

“He’s a real progressive dude,” says the veteran pol. “More progressive than people realize.”

We’ll see.