CHICAGO >> With only a few days to go, Richard M. Daley, the longest-serving mayor in Chicago’s history, had yet to pack up his City Hall office, which was cluttered with old photographs, trinkets from other towns, even the desk from which his father once governed this city.

Desk or no desk, however, Rahm Emanuel was already sounding like the mayor. He announced that outsiders would lead the Police Department and the school system. He pressed for state legislation that would let him increase the length of Chicago’s school days. He warned of painful budget cuts immediately ahead, $75 million in his first 100 days.

“We can’t continue with the government we have,” Emanuel said in an interview in a hotel lobby down the street from City Hall. “It has not been fundamentally reformed.”

After 22 years under the reign of a single, singular mayor and much of the last half-century with someone named Daley at the helm, even the slightest adjustment would feel enormous to Chicago. But Emanuel, who will officially take over on Monday after a ceremony in Millennium Park, the city’s front yard, is promising seismic shifts.

A 71-page, slickly bound transition plan Emanuel issued last week mentioned the word “change” 19 times. Many here — including members of a City Council accustomed to Daley, whom they rarely bucked, and city workers, who fear that Emanuel will clean house, cut benefits and privatize city services — are bracing for something Chicago, the nation’s third largest city, has rarely known: the unknown.

“You don’t have a crystal ball,” said Jorge Ramirez, president of the Chicago Federation of Labor, which chose to endorse no mayoral candidate in the February election that Emanuel won with 55 percent of the vote.

But if Emanuel, who is 51 and will become this city’s first Jewish mayor, seems intent on changing Chicago, this city, too, seems certain to change Emanuel.

Known for his frenetic, blunt, relentless style, Emanuel, who has been a top adviser to two presidents and a member of Congress, will for the first time work as an elected chief executive. And while machine politics may have faded in Chicago, old alliances and neighborhood tribalism are hardly forgotten, and voters expect their mayor to spend time plenty of time with them. All of this as the city, shrinking in population, is facing a budget crisis of crippling proportion.

“It is an enormous challenge,” said Dick Simpson, a political scientist at the University of Illinois who once served as one of the city’s 50 aldermen. “He’s going to have to find a way to build consensus, collaborations and cooperation to an extent he hasn’t ever had to do at the White House.”

Emanuel has been walking a careful line: saying sweeping changes are needed, but, at the same time, never quite pointing out a failing or misstep by Mayor Daley.

The two men are Democrats, political allies and personal friends. Long ago, Emanuel raised money for one of Daley’s campaigns. Though Daley never publicly chose sides in the mayoral race last winter, he is widely believed to have given a tacit nod to Emanuel. And Emanuel said he had been consulting with Daley lately. “I would be crazy not to call on him,” Emanuel said.

Besides, critiquing the mayor might not be politically wise. Although voters here like to moan about his dictatorial style and imperfect syntax, Daley has won six elections, and seemed likely to win another had he not decided to retire. For weeks, Daley has been conducting a farewell tour of neighborhoods, and banners in the city read, “Chicago; A World-Class City; Thank You Mayor Daley.”

Emanuel, too, is effusive about his city. But he also has plans — lots of them. He wants Chicago parents to start signing “parent-teacher agreements” at the start of each school year, laying out expectations for learning that will happen at home. He wants to ban mayoral appointees from instantly turning around and lobbying City Hall colleagues when they leave office. He wants to streamline licensing for businesses. He wants to shrink City Council committees. He wants to freeze spending, and tackle unfunded pension liabilities, a politically fraught realm.

So many ideas may quickly land Emanuel in his first clashes with Chicago’s vast City Council, with all its disparate alliances and with one of its most powerful and veteran members, Edward M. Burke, having worked against Emanuel’s candidacy.

Some aldermen — few are willing to speak publicly in unflattering tones about the arriving mayor — already sound a bit skeptical.

“We’ve had enough promises of reform, scorecards and far-off dates,” Ric Munoz, an alderman, said of Emanuel’s transition plan, which Munoz said sounded more like a set of campaign pledges. “When the administration is serious about reform, I will be with them.”

But Emanuel said he had already met with all 50 aldermen — a group that, notably, will not look the same as it did under Mayor Daley. Thirteen new aldermen were elected this year, and some who had never held chairmanships of committees are now expected to.

“I have had more conversations with this mayor and his top aides in the last month than I did in the last two years with the last mayor,” said Joe Moore, an alderman who has sparred with Daley over the years. “There’s an opportunity for everyone to push the reset button.”

Ordinary Chicagoans, meanwhile, are watching. Residents said they were waiting to see whether Emanuel will really turn up to their ribbon-cuttings, community center openings and basketball tournaments (a habit they adored in Daley). Will he relax enough — or unwind, in the words of Andy Shaw, leader of the Better Government Association — to soak in the more mundane, everyday moments of this new job?

Daley was long viewed here as Mayor for Life. In part that meant he did not covet some grander political job and everyone knew that. But Emanuel, who has already had to defend his Chicago ties in a peculiar election challenge that nearly toppled his candidacy, enters with the opposite presumption about him.

“I’m 100-percent focused on being mayor,” Emanuel said the other day. “I’m not interested in any other job in public life.”

Chicago, it seems, wants to be convinced. Inside and outside the political sphere here, people say they presume Emanuel, known for his ambition and drive, will be on to some bigger, fancier chapter eventually. One guessing game among political analysts even before the swearing in: Will it be a presidential run or a governor’s race that eventually woos him away?