Over the past several months, Mr. Tusk orchestrated the abortive Harold Ford Jr. campaign against Kirsten Gillibrand, a frequent target of the mayor's ire; he ran the political operation of a group of charter school advocates, working alongside the mayor's own efforts, to lift the cap on charters throughout the state; and he has signed on as the top adviser to Staten Island District Attorney Dan Donovan, convincing the friend and golfing buddy of the mayor that there's a Republican path to the attorney general's office this fall.

Mr. Tusk's informal status as the mayor's go-to guy has its benefits for both sides. Mr. Tusk provides the outsource-able political muscle--capable of acting as a cudgel to supplement the administration's efforts from the outside--and at the same time reaps the returns of a particular, and potentially lucrative, niche on the flank of Team Bloomberg.

"The mayor cares about one thing, and that's who can get the job done. If you can get the job done, he wants you on his team," said Ed Skyler, a former deputy mayor and Mr. Tusk's best friend.

A source close to the mayor puts it more bluntly: "Not only does he want Bradley on his team, he wants him to be a quarterback."

It was Mr. Skyler who brought his friend into the Bloomberg orbit in 2002 for a one-year stint in the mayor's office. The two had met at Henry Stern's Parks Department in the mid-1990s; they had both graduated from Penn the same year, but hadn't known each other. Mr. Tusk had met Ed Rendell, then the mayor of Philadelphia, in 1992 and had become an intern in Mr. Rendell's office, which allowed him to forgo the poli-sci department and major in creative writing instead.

"His parks name was Ivory," said Mr. Stern, who thought Mr. Tusk's ability stood out even among the young talent in his department.

Mr. Tusk went off to law school at the University of Chicago, studied under Cass Sunstein, and brought back some of the scholar's social norms theory-including the use of shame to affect social behavior-to Mr. Stern and the Parks Department.

"Ivory thought up a slogan we put on signs: 'If you don't clean up after your dog, you don't deserve to own one,'" Mr. Stern recalled.

He left for Mr. Schumer's office, and later decamped for a career-making job as the deputy governor of Illinois to Rod Blagojevich.

Mr. Tusk came back to New York to work at Lehman Brothers. When Lehman collapsed, his friends in the mayor's office recruited him back with the promise they would keep him busy. He ended up wrangling support for the term-limits extension, and then, for the reelection effort, as campaign manager--his first job on a campaign.

It was a strange one.

The idea was to project the inevitability of Mr. Bloomberg's reelection, even though internal polls showed it to be a close race. The strategy stood to make Mr. Tusk's $100 million campaign look underwhelming when the numbers rolled in.

"Bradley knew what the margin would mean for him professionally and he could have easily put out stories sort of lowering expectations," Mr. Skyler said. "Bradley basically put the mayor first and him last. And I think long term, people recognize that."

But for Mr. Tusk, who is now hanging a shingle as Tusk Strategies, being on Team Bloomberg makes for a unique niche, one that could prove difficult to navigate.

Mr. Tusk's lusty embrace of the Bloomberg operative-for-hire role has paid dividends for him, but it also irrevocably altered his relationship with the New York Democratic Party, and in particular with the man who may well be the next leader of the U.S. Senate.

"Clearly, there were people who I like and respect, who define the party's position, who didn't want me to do that," said Mr. Tusk of his work for Mr. Ford. "At the end of the day, if I think candidate X is better than candidate Y, and X calls me to help them, I'm going to take it. That's just the way I am."

"I think in New York City it has now become fairly common for Democratic consultants to work for an independent candidate, and I think that's a reflection that a lot of New York voters have voted for an independent candidate," said Howard Wolfson, the longtime Democratic operative, who now works for Mr. Bloomberg.

But Mr. Tusk's decision to handle a Republican candidate for attorney general--even a relatively moderate one like Mr. Donovan--is a step across the aisle that many of his fellow Democratic consultants have been unwilling to take.

Mr. Tusk scoffs at the possibility that such blatant party-crossing could cost him the top candidates in both parties.

"Would I love to run a presidential campaign someday? Sure, theoretically, it would be fun. ... If some Republican or Democrat who I like and want to work for believes I'm the best person, they're going to hire me. I firmly believe that."

"It's something you can do," said Hank Sheinkopf, the longtime Democratic consultant who worked with Mr. Tusk on the mayor's most recent reelection and said the young operative would be in his top-five people to have in a foxhole with him. "When the mayor's not in office, it will be a little more difficult. We don't know yet what the Bloomberg legacy will be."

Mr. Tusk sees his role broader than the Bloomberg orbit. He has unrelated corporate clients and is currently working pro bono on Ed Koch's New York Uprising campaign for nonpartisan redistricting (it also employs two former Bloomberg aides), and sees his success on charter schools as the first of what could become a model for battling entrenched special interests in Albany.

"What I'd like to do is take that general set of policies and figure out, how do we corral all these different people and resources, who agree on all these different principles, to have one effort to get things done?" Mr. Tusk said.

"The era of the union special interests may be over as we know it--for the time being," said Mr. Sheinkopf. "So Bradley Tusk may be the right guy at the right time. This may be his moment."

rpillifant@observer.com

Options for the developer-legendary in development circles for his speed-will soon start to narrow.

Prodded by an aggressive and politically powerful hotel union, the Bloomberg administration is opening a battle against the proliferation of such hotels, the lower-cost, no-frills ones that have been the bulk of the city's hospitality growth in the latest real estate cycle.

The first salvo in the battle: A rezoning of the 25-block district in northern Tribeca, which began the public approval process last week and includes the restriction that any new moderately sized hotel could be blocked by the City Council. City officials have also committed to similar restrictions in a long-planned rezoning of the garment district in midtown south and of Industrial Business Zones, manufacturing-focused areas that allow hotels.

The result is a relatively small but not insignificant chunk of Manhattan that will be off-limits to the likes of Mr. Chang-or certainly unavailable in the same manner, and at the same cost, at which such developers have been proceeding.

This policy, a top priority of the hotel union that would seem anathema to the normally pro-development Bloomberg administration, appears to be only in its nascent stages, as northern Tribeca and the other rezonings lay out a template for other neighborhoods.

The main force behind the push-back against the limited-service hotels is Peter Ward, the president of the New York Hotel & Motel Trades Council. His union is threatened by the explosion of such hotels-since 2005, the union estimates that more than 13,000 rooms in limited-service or boutique hotels have been developed or are in development. Given that the vast majority of the limited-service and boutique hotels have small staffs and are non-union, this draws business away from some venues that employ Mr. Ward's membership.

By requiring new hotels to go before the City Council in these districts, the theory is that the generally labor-friendly Council would demand that the developers allow for easy unionization within the hotels before they are approved. (In northern Tribeca, hotels under 100 rooms would be exempt.)

"Part of what we're seeing is something that we've never seen in New York City," Neal Kwatra, political director for the hotel union, said of the limited-service and boutique hotel explosion. "We don't know what the net impact will be on those neighborhoods that have never had that hotel product.  We think it's prudent for the city to retain some flexibility as it relates to these developments." 

MORE THAN ANYTHING else, the new policy speaks to the increasing power of a union that has carefully forged political alliances to the point where it was able to push an agenda on a pro-development, billionaire mayor.

Contrast that to, say, the Retail, Wholesale, and Department Store Union, which is pushing a bill for a living-wage standard in city-subsidized retail developments. The mayor, who has a poor relationship with RWDSU president Stuart Appelbaum, has dismissed the living-wage concept as unfeasible, and the bill is viewed as facing an uphill battle even in the labor-friendly Council.

By contrast, Mr. Ward, persistent and tenacious, has a history with the mayor, and his union has built up an effective political organizing arm. Mr. Ward was a staunch supporter of one of the mayor's pet projects, a Jets stadium on the far West Side, and last year, when Mr. Bloomberg was seeking support from labor leaders for his reelection, the two went to a Yankees game together.

Electorally, the hotels union has become a major force, a fact not lost on any elected official who is weighing legislative or policy requests from Mr. Ward. Led by Mr. Kwatra, a talented operative with slicked-back black hair, the political arm is able to lend its door-knocking and organizing operation to candidates it supports (or against those it opposes), giving heft to its endorsements.

Take, for example, the situation at Tavern on the Green. As the mayor began gearing up for a third term-at the start of his process of cultivating endorsements-the union negotiated a deal with the city that effectively required any new operator to use union labor, a big win for the organization (the hotel workers' union also represents restaurant workers). But earlier this spring, the new operator, Dean Poll, failed to reach a deal with the union; talks broke apart, Mr. Poll withdrew, and the vacant restaurant now awaits an operator that would, presumably, have to be ready to negotiate with the union.

As for the union's land-use battle against limited-service hotels, resistance is relatively muted, in part because there is no effective structure in place to resist it.

The restrictions, after all, are sure to repress development of hotels in the targeted districts, given the added costs of unionization. "At the end of the day, this would tie the hands against a lot of the limited-service product that has gone up," said John Fox, a hotel analyst at PKF Consulting.

But the developers of such hotels are generally not the most politically connected in New York City. Rather, they tend to be younger or less prestigious developers who lack the political gamesmanship to counter the union. There is no politically strong limited-service hotel coalition, and the Hotel Association of New York City is dominated by members who must by contract have a unionized workforce. (The association's president, in a statement, supported the northern Tribeca rezoning as a "prudent public policy measure.")

The real estate industry's main lobbying arm, the Real Estate Board of New York, is opposed to such restrictions, but it does not seem ready to go to the mattresses. "We're against it," REBNY president Steven Spinola said. "The issue is, clearly, why are you making things complicated? What this is going to force people to do is to go make a deal with the unions."

ON ITS FACE as a policy matter, this is not the type of issue the pro-development Bloomberg administration would typically take up on its own.

This is not to say that there is no policy justification. The union's line-which has more merit in certain areas of the city than others-is that hotels can be particularly noxious to street life. They are densely packed, with tourists and visitors coming and going constantly throughout the day. They're more likely to have bars or clubs than apartment buildings of similar size; deliveries are far more frequent. In many parts of Manhattan, they have shot up in tall, skinny structures that are often out of scale with surrounding buildings.

Thus, the solution, from the hotel union's perspective, is to examine each hotel individually. Functionally, new hotels in the delineated districts would require a special permit, one that requires approval from the City Planning Commission, which the City Council can, in turn, veto. Typically, most development of apartments or hotels can be done freely by a developer, but an automatic requirement for a special permit puts hotels in the same category as large parking garages or electric substations. 

"The overall impact is to make hotels fit into the neighborhoods that they go up in, and have them more integrated into the neighborhoods," Kevin Finnegan, an attorney who worked on the union's pitch, said of the plan. "The impact of hotels is high-there's a lot of people moving in and out."

(There's a bit of irony here: The hotel union is arguing that hotels can be a negative for neighborhoods, but apparently it's worth the gain.)

In terms of northern Tribeca, the administration is pushing the neighborhood character argument, saying that specific regulation is needed for certain neighborhoods.

"Northern Tribeca is located within one of the city's existing Special Districts, which enable this kind of tailored regulation based on unique area needs," Andrew Brent, a spokesman for the mayor, said in a statement. "Requiring a special permit for hotels in Northern Tribeca would help ensure large, new hotels don't interfere with the character of the neighborhood."

As for whether the agreed-upon districts will give way to more of them, Mr. Brent did not rule out the concept.

"Whether such a provision will be warranted in future rezonings remains to be seen," he said. "They are done individually and one does not set a uniform precedent for another."

ebrown@observer.com