In that book, Mr. Obama paints a portrait of himself as a genuine reformer and change agent, just as he has in this presidential campaign. He attributes his 1996 victory to his message of hope, and his exhortations that Chicagoans drop their justifiable cynicism about politics.

When voters complained of all the broken promises politicians had made in the past, Mr. Obama writes that he "would usually smile and nod, and say that I understood the skepticism, but that there was -- and always had been -- another tradition to politics, a tradition based on the simple idea that we have a stake in one another, and that what binds us together is greater than what drives us apart, and that if enough people believe in the truth of that proposition and act on it, then we might not solve every problem, but we can get something meaningful done."

Mr. Obama writes that even if the voters were not impressed by this speech, "enough of them appreciated my earnestness and youthful swagger that I made it to the Illinois legislature."

In real life, it did not matter what Mr. Obama said on the stump or whether South Side voters were impressed. What mattered was that, beginning on Jan. 2, 1996, his campaigners began challenging thousands of petition signatures the other candidates in the race had submitted in order to appear on the ballot. Thus would Mr. Obama win his state Senate seat, months before a single vote was cast.

According to the Chicago Tribune, Mr. Obama's petition challengers reported to him nightly on their progress as they disqualified his opponents' signatures on various technical grounds -- all legitimate from the perspective of law. One local newspaper, Chicago Weekend, reported that "[s]ome of the problems include printing registered voters name [sic] instead of writing, a female voter got married after she registered to vote and signed her maiden name, registered voters signed the petitions but don't live in the 13th district."

One of the candidates would speculate that his signature-gatherers, working at a per-signature pay rate, may have cheated him by signing many of the petitions themselves, making them easy to disqualify.

In the end, Mr. Obama disqualified all four opponents -- including the incumbent state senator, Alice Palmer, and three minor candidates. Ms. Palmer, a former ally of Mr. Obama, had gathered 1,580 signatures, more than twice the 757 required to appear on the ballot. A minor, perennial candidate had gathered 1,899 signatures, suggesting the Obama team invested much time working even against him.

The act of throwing an incumbent off the ballot in such a fashion does not fit neatly into the narrative of a public-spirited reformer who seeks to make people less cynical about politics.

But Mr. Obama's offenses against the idea of a "new politics" are many, and go well beyond hardball election tactics. It is telling that, when asked at the Saddleback Forum last weekend to name an instance in which he had worked against his own party or his own political interests, he didn't have a good answer. He claimed to have worked with his current opponent, John McCain, on ethics reform. In fact, no such thing happened. The two men had agreed to work together, for all of one day, in February 2006, and then promptly had a well-documented falling-out. They even exchanged angry letters over this incident.

The most dramatic examples of Mr. Obama's commitment to old-style politics are his repeated endorsements of Chicago's machine politicians, which came in opposition to what people of all ideological stripes viewed as the common good.

In the 2006 election, reformers from both parties attempted to end the corruption in Chicago's Cook County government. They probably would have succeeded, too, had Mr. Obama taken their side. Liberals and conservatives came together and nearly ousted Cook County Board President John Stroger, the machine boss whom court papers credibly accuse of illegally using the county payroll to maintain his own standing army of political cronies, contributors and campaigners.

The since-deceased Stroger's self-serving mismanagement of county government is still the subject of federal investigations and arbitration claims. Stroger was known for trying repeatedly to raise taxes to fund his political machine, even as basic government services were neglected in favor of high-paying county jobs for his political soldiers.

When liberals and conservatives worked together to clean up Cook County's government, they were displaying precisely the postpartisan interest in the common good that Mr. Obama extols today. And Mr. Obama, by working against them, helped keep Chicago politics dirty. He refused to endorse the progressive reformer, Forrest Claypool, who came within seven points of defeating Stroger in the primary.

After the primary, when Stroger's son Todd replaced him on the ballot under controversial circumstances, a good-government Republican named Tony Peraica attracted the same kind of bipartisan support from reformers in the November election. But Mr. Obama endorsed the young heir to the machine, calling him -- to the absolute horror of Chicago liberals -- a "good, progressive Democrat."

Mayor Richard M. Daley -- who would receive Mr. Obama's endorsement in 2007 shortly after several of his top aides and appointees had received prison sentences for their corrupt operation of Chicago's city government -- was invested in the Stroger machine's survival. So was every alderman and county commissioner who uses the county payroll to support political hangers-on. So was Mr. Obama's friend and donor, Tony Rezko, who is now in federal prison awaiting sentencing after being convicted in June of 16 felony corruption charges. Rezko had served as John Stroger's finance chairman and raised $150,000 for him (Stroger put Rezko's wife on the county payroll).

Mr. Obama has never stood up against Chicago's corruption problem because his donors and allies are Chicago's corruption problem.

Mr. Obama is not the reformer he now claims to be. The real man is the one they know in Chicago -- the one who won his first election by depriving voters of a choice.

"Barack Obama’s ad is ridiculous. Because of John McCain, corruption was exposed and people like Jack Abramoff went to jail.

"However, if Barack Obama wants to have a discussion about truly questionable associations, let’s start with his relationship with the unrepentant terrorist William Ayers, at whose home Obama’s political career was reportedly launched. Mr. Ayers was a leader of the Weather Underground, a terrorist group responsible for countless bombings against targets including the U.S. Capitol, the Pentagon and numerous police stations, courthouses and banks. In recent years, Mr. Ayers has stated, 'I don’t regret setting bombs … I feel we didn’t do enough.'

"The question now is, will Barack Obama immediately call on the University of Illinois to release all of the records they are currently withholding to shed further light on Senator Obama’s relationship with this unrepentant terrorist?" --McCain spokesman Brian Rogers

Had Ayers actually apologized for his radical terrorism as a member of the Weather Underground, Daley’s lament would make sense. In fact, though, Ayers has repeatedly refused to apologize for his bombings and his terrorist actions, nor has his wife Bernardine Dohrn repented of her connections to bombings, thefts, and murder. To this day, they still speak publicly about the need to overthrow the capitalist system of the United States and call America a "monster".

They’re friends. So what? Well, most Americans don’t have friends who plotted to bomb the Pentagon, or assisted radicals in robberies that resulted in murder. Not only did Barack Obama make these people his friends, he worked closely with them on two separate projects, the Woods Foundation — and that pesky Chicago Annenberg Challenge that UIC, a public institution, ran. These were voluntary associations, not a case of both being hired by a corporate manager and forced to work together. In fact, Obama chose to work for Ayers at the CAC.