MICHAEL NUTTER has moved to the brink of becoming Philadelphia's next mayor with a convincing win in a Democratic primary that reshaped the city's politics as dramatically as the towering cranes now remaking its skyline.

The 49-year-old self-styled reformer with an Ivy League pedigree won with more than a third of the vote - well ahead of a second-place showing by wealthy outsider Tom Knox and three Democratic stalwarts who faltered badly.

"We have to change the direction of this city," an ebullient Nutter told cheering supporters at the Radisson Plaza-Warwick Hotel Philadelphia just after 11 p.m. He said many people are unhappy with the current state of Philadelphia - "but that was yesterday."

Nutter, a Wynnefield resident who spent 14 years on City Council, is not yet Philadelphia's 98th mayor. But it would take a political miracle for obscure Republican Al Taubenberger or any independent challenger to end the Democrats' 56-year-grip on power this November.

In the end, this election may be recalled not just for who won but for how it was conducted - with little of the race-based politics and invective that has dominated contests here for decades, and with voters clearly hungering for a new direction from traditional machine politics.

"This campaign was about change," said G. Terry Madonna, the political scientist and pollster from Franklin & Marshall College. He said city voters wanted to replace Mayor Street with someone who would fight crime and corruption - but "they didn't trust a complete outsider, so they went with an insider-outsider."

City voters resoundingly rejected the two candidates most closely tied to the entrenched Democratic establishment, Reps. Bob Brady and Chaka Fattah. State Rep. Dwight Evans, frequently lauded for his ideas but not his style on the stump, finished a distant fifth, ahead of perennial candidate Queena Bass and Jesus White, the first homeless candidate for mayor.

What did it take for America's now-sixth-largest city to finally take a giant step toward shedding the "corrupt and contented" label that muckraker Lincoln Steffens saddled it with more than a century ago?

A lot, actually. There were a couple of political bombshells along the way, including a City Hall corruption scandal that ensnared a host of characters including the mayor's own brother, and perhaps lingering resentment for the 2006 midnight legislative pay raise.

Another factor may have been an extreme makeover - of Philadelphia itself.

For decades, the city's politics was defined by its rapidly shrinking population, a sense of pessimism and the strong issues of race and identity that seemed to come with that decline. That divide came to be symbolized in particular by one man - divisive law-and-order mayor and police commissioner Frank Rizzo - who seemed to loom over every election from the mid-1960s until 1999, when his former top lieutenant Marty Weinberg narrowly lost to Street.

But today, there's a new generation of Philly voters who best know the senior Rizzo as a statue in front of the Municipal Services Building. And the city's population loss has slowed to a trickle, aided by newcomers - from empty-nesters to hip New York refugees with no connection to the politics of the past.

From almost the beginning, two mayoral candidates tapped into the electorate's newfound yen for reform - but with radically different approaches.

One was millionaire businessman and former Ed Rendell mayoral aide Knox - who spent a whopping $10 million plus of his own money and raced to an early lead in the race with a promise to clean up corruption in City Hall.

Nutter was the first candidate to formally enter the race last year, and his campaign strategy looked a lot like the race that Street Sense just ran in the Kentucky Derby - hanging back in the pack much of the way, and then an explosive burst of energy on the final turn.

Ed Turzanski, a La Salle University administrator and political pundit, said a turning point came when the other candidates, especially Brady, turned their fire on frontrunner Knox, attacking his business practices and political donations that seemed to undercut his claims of being a reformer. In the end, Knox spent $143 for every vote he received.

Unlike Knox, Nutter - a 14-year veteran of City Council - could not claim the mantle of outsider, but he did have a legislative record of reform, including passage of the city's first major campaign-finance overhaul.

"He has steered clear of most of the insider political entanglements and was not particularly tied to the machine," Turzanski said.

When Nutter finally did take to the airwaves, his campaign quickly showed a flair for the unorthodox - and it worked. His first ad highlighted Nutter's differences with someone not even on the ballot - longtime nemesis Street - but it apparently registered with reform-minded voters, also cutting across racial lines.

Madonna noted that in this election, black, white and Latino voters shared similar concerns about crime and education, which reduced the opportunities for polarization. He also noted that Nutter took the most "bodacious" stances on those key issues, especially his aggressive "stop-and-frisk" proposal for dealing with crime.

Nutter's second major ad, featuring his 12-year-old daughter Olivia, offered a touch of light humanity that was a striking contrast to Philadelphia's tradition of brass-knuckle politics.

As Nutter surged to the lead, polling showed he was getting a level of white support that was unpredecented for an African-American in Philadelphia in a high-profile, multi-candidate race.

That reflected both changes in the electorate but also the fact that Nutter was a different kind of black candidate - one who had not emerged from the city's contentious racial politics of the 1970s and '80s, as had Goode and Street. In fact, Nutter - a graduate of the University of Pennsylvania's Wharton School - was an investment banker during the 1980s.

Not surprisingly, Philadelphia had a rather quiet Election Day, in keeping with the overall tone of the campaign. There were few reported incidents at the polls; the most widely reported irregularity didn't involve ballots but bucks - $550 robbed from a Knox field office. Turnout was reported at about 30 percent - solid, not spectacular.

"The fact there wasn't a really charismatic candidate in this race" kept turnout from being higher, said Zack Stalberg, CEO of the Committee of Seventy. "That's what it takes, a really strong personality, positive or negative."

In the end, the strongest personality yesterday may have been the Philadelphia voter. *

Staff writer Gloria Campisi contributed to this report.