CHICAGO — Chicago politics, viewed from afar, often seems a monolithic thing. The words most closely associated with it — "the machine" — imply an implacable, unbreakable force. On the ground, nearly the opposite is true.

Far from being a monolith, the machine has many parts.

Anyone seeking to navigate and survive it, much less prosper, must master a set of equations that includes fine gradations of locale and clan. There are, just for starters, the South Side and the Near North Side, the Loop, the South Loop, the West Loop, West Town, Irving Park, Portage Park, Hyde Park, this Catholic parish or that, the Poles and the Czechs.

You'll encounter a hundred fiefdoms without ever leaving Cook County, beyond which lie still more divisions: the collar counties around the city, and, of course, downstate, from the northwest suburbs to the sundown towns — as in, if you were black, you'd better be out of town before the sun set.

It is a place, in other words, of great divisions and, maybe because of that, uncommonly well-suited to have initiated U.S. Sen. Barack Obama into politics.

Obama-mania has exploded across the country, propelled by a wave of adulation that greeted the publication of his second book, "The Audacity of Hope," and by shrewd manipulation of the opportunity that attention afforded. He has popped up everywhere, from the cover of Men's Vogue to "Monday Night Football." He has been urged to run for president by everybody from Oprah Winfrey to a shockingly large number of ideologically opposed political commentators.

For the moment, the Honolulu-born Obama has demurred. A decision, he has said, will be forthcoming after the New Year. His sister, Maya Soetoro, said last week that he would decide during his holiday visit with family and friends in Hawai'i and probably would announce it after returning to Illinois.

Hardly anybody who knows Obama doubts that he wants to run. But he has two young children, and whether he enters the race for the 2008 Democratic nomination will be largely a family matter, friends say.

OUTSIDER TAKES CHICAGO

Obama, a Punahou School alumnus, arrived in Chicago in 1991, unbidden, with a fresh Harvard Law degree, big ambitions and virtually no reason to think they would ever be fulfilled. In a place of fervid group loyalties, he was a nearly complete outsider, having spent just three of his prior 30 years in the place, a member of no group but his own.

Five years later he was elected to the state Senate. He was re-elected in 2000, then won election to the U.S. Senate in 2004. What he had instead of a loyal base was a million-dollar smile, an optimistic message of inclusion and a willingness to work with anyone willing to put a shoulder to the wheel of his choosing, no matter their ideological stance.

Chicago politics tends toward polarization. Depolarization is Obama's stock-in-trade.

Just a generation ago, when Harold Washington was campaigning to become the first black mayor of Chicago, he and Democratic presidential candidate Walter F. Mondale attended Sunday Mass at St. Pascal's, a white Roman Catholic parish in Northwest Chicago. They were spat upon, cursed and lucky to leave unharmed.

In his 2004 Senate campaign, Obama carried every precinct but one, in St. Pascal's Portage Park neighborhood. Talk to people who live there now and you could get the impression that Obama grew up one block over.

Why?

"Barack is wildly less threatening than Harold Washington," said Judson Miner, who hired Obama into his small Chicago civil rights law firm in 1991. "Even the North Shore ladies love him."

Go west to DuPage County, one of the most Republican in the nation, and you'll find a GOP county chairman, state Sen. Kirk W. Dillard, who relishes the opportunity to accompany Obama whenever he comes to town. "My constituency is enamored of him," Dillard said. That Obama registered approval ratings in DuPage above 60 percent in fall's campaign season is an obvious reason to get next to him, but Dillard has been on the Obama bandwagon for years.

He, along with many others, were skeptical when Obama arrived in Springfield, the state capital. There was suspicion that Obama, with his fancy degrees and a job teaching constitutional law at the University of Chicago, was an elitist. It turned out he was a more or less regular guy who played pick-up basketball and poker.

Obama developed a reputation as a very conservative poker player. He threw in many more hands than he played, said another Senate colleague, Larry Walsh. "I told him once, 'If you were a little more liberal in your poker-playing and a little more conservative in your politics, we'd get along a lot better.' "

Obama was somebody you could have a beer with, Walsh said, even if Obama, who frequently quit buying but not smoking cigarettes, perpetually bummed them.

SIGNS OF A 'ROCK STAR'

As a freshman, a member of a Democratic minority in a General Assembly not much interested in policing itself, Obama carried to passage the state's first significant ethics legislation in a generation. He later worked to reform the state's death penalty and healthcare laws. He developed a reputation as someone anybody could work with.

"I brag that before anybody knew who he was, I knew he had the gifts that have made him into the rock star he is — charm, intellect, hard worker, ability to relate," Dillard said.

In "The Audacity of Hope," Obama tells of being on the floor of the state Senate, sitting with a white colleague. A black senator, whom Obama refers to as John Doe, gave a lengthy, passionate speech in which he said voting against the program he was speaking for would be racist. The white colleague, a liberal, turned to Obama and said, "You know what the problem is with John? Whenever I hear him, he makes me feel more white."

Obama sees this as an illustration of the exhaustion of white guilt. He has nearly the opposite effect on people; he removes race from the equation.

Some critics would say he works too hard at this, yet there is no one in contemporary American politics who has gone to greater lengths to define and embrace his racial identity. He wrote an entire memoir, "Dreams From My Father," about that act of definition. "My identity might begin with the fact of my race, but it didn't, couldn't end there. At least that's what I would choose to believe," he wrote.

'THIS IS NOT AN ACT'

In many ways, Obama is both politician and celebrity. He is one of very few politicians who cause a rustle just entering a room. Heads turn, cameras flash and whooping and hollering commence often before he reaches the stage. People offer up their children for hugs and scramble for autographs.

Emil Jones Jr., president of the Illinois Senate and one of Obama's mentors, tells the story of attending a downstate political dinner where he, his driver and Obama were the only black faces in a crowd of 3,000 people.

"Sitting across the table from me was a little old lady, said she was 86 years old," Jones said. "After Barack spoke, she nudged me on the shoulder and said, 'This young man is going to be president of the United States some day. I just hope I live long enough to vote for him.' "

Obama was utterly unknown outside Illinois until he was chosen to deliver the keynote address at the 2004 Democratic National Convention in Boston. Watching that speech from the convention floor, Jones was astounded to find tears rolling down his face. He was embarrassed, he said, until he saw another delegate crying too. "It's the most amazing thing I've ever seen in 40 years in politics," Jones said.

People who have known Obama for a while tend to describe him in ways that are eerily similar to the way he is described by people who know him hardly at all. "The biggest difference between then and now is he's been well-publicized," said state Sen. Terry Link, another legislative colleague. "A lot more people know him, but he's the same guy. I've spent a lot of quiet nights with him. This is not an act by any means."

What is most striking about the surge of interest in Obama is the degree to which it is fueled by people's estimation of him as an individual, not as a politician. His appeal is almost entirely personal.

Abner Mikva, a former federal judge and Illinois congressman who taught with Obama at the University of Chicago, said Obama was probably the smartest man he had ever met. Yet people typically saw him as the next-door neighbor they would love to have: "He's Everyman. People look at him and see what they want to see. Not that he cuts and trims. They fit him into what they want."

This is probably not an accident. Obama's political skills are in some ways reflected in his personal history. Born half Kenyan, half Kansan, and raised in polyglot places such as Honolulu and Jakarta, Indonesia, he has spent much of his life as an outsider figuring out a way to fit in. As a consequence, friends say, there is no place Obama doesn't feel at ease, no room he's uncomfortable entering.