There was, once, a slender chance that this would be the best mannered election in recent times. It was in both candidates’ interest to mount campaigns devoid of dirty tricks and negative campaigning.

John McCain suffered during the 2000 Republican primary in South Carolina and discovered the hard way that in modern politics anything goes.

Texas National Guardsman Bush stood silently by as surrogates besmirched the war hero. It was whispered Mr. McCain was unsuited to become president because he had become deranged after years of torture, that he was a “Manchurian candidate” who would become a communist puppet, that his adopted Bangladeshi daughter was his own illegitimate child.

It was, of course, all a big lie. Mr. McCain pleaded with Mr. Bush to call off his attack dogs, but the governor shrugged his shoulders, claiming ignorance of who was behind the slime. In defeat, to the chagrin of many conservatives, Mr. McCain has fought to silence the sort of independent political groups that stopped his ambition in its tracks.

Mr. Obama, too, would benefit from a clean fight. As an inexperienced campaigner, the first African-American nominee, and a Chicago South Side politician with plenty of baggage, he will find it difficult to counter the activities of well funded 527 groups. He can be sure that footage of the Reverend Jeremiah Wright’s bilious sermons are already being crafted into campaign ads.

Amid cries of foul, Mr. McCain has been drawing attention to Mr. Obama’s shortcomings in a series of unflattering ads, but anyone who observes politics for a living knows the “negative campaigning” this time amounts to little more than handbags at dawn.

Mr. Obama’s aides know how to fight dirty. They did not need to read Arthur Miller’s “The Crucible,” or David Mamet’s “Oleanna,” or Terence Rattigan’s “The Winslow Boy” to grasp the devastating effect of wrongful accusations, and they successfully silenced Bill Clinton and crippled Hillary Clinton’s campaign by suggesting that the president, of all people, was a racist.

President Clinton was left deeply hurt by the accusation, but the mud stuck. The traducing of the man Toni Morrison, no less, described as “our first black president. Blacker than any actual black person who could ever be elected in our children’s lifetime,” is one of the chief reasons many of the 18 million who backed Mrs. Clinton still find it hard to love Mr. Obama.

When Mr. Obama declared Mr. McCain would frighten electors by pointing out “he doesn’t look like all those other presidents on those dollar bills,” Mr. McCain called him out, accusing the Illinois senator of dealing the race card “from the bottom of the deck.” Mr. Obama sputtered, at first claiming he wasn’t referring to race, then admitted he was indeed using the same trick he had so successfully played against the Clintons.

Deprived of preemptive accusations of racism, the Obama camp has continued to cry foul against Mr. McCain for suggesting its candidate is not ready to lead, would not make a good commander in chief, is preparing to withdraw from Iraq too quickly, was slow off the mark to condemn Russia for invading Georgia, and many other legitimate concerns.

When Mr. McCain compared him to Paris Hilton and Britney Spears, to suggest Mr. Obama makes a better celebrity than chief executive, the Obama apologists once more cried “race” because — this from the New Yorker’s Hendrik Hertzberg — “… it cannot have escaped the ad makers’ notice that [Spears and Hilton] also symbolize white, blond sexual availability.” Perhaps if you have a dirty mind, anything can seem racist, or sexist, or sexual. But sometimes, as Sigmund Freud might have said, a fountain pen is just a fountain pen.

Despite railing against knocking copy, Mr. Obama has not hesitated to indulge in negative campaigning of his own. By jumping on Mr. McCain’s admission he wasn’t sure how many homes he owns, the suggestion being that the McCains are so filthy rich they cannot possibly understand the concerns of ordinary Americans — the very charge that is so often leveled against Mr. Obama — he has opened the door to a hurricane of low, dirty, unfair ads from the Swiftboaters of 2008.

Since when is class warfare warranted in America, the land of opportunity? Since when has wealth, or a wife’s wealth, become the benchmark by which candidates are to be judged? What sort of envious, angry, carping, inverted snobbery inspires such thoughts? Did the number of homes Franklin Roosevelt or John Kennedy have mean they did not care for the common man?

By his action, Mr. Obama has invited scrutiny into why the convicted felon, Tony Rezko, helped him pick his home, and why Mrs. Rezko bought the next door plot and cheaply sold him a strip to enhance his property’s value. And he has drawn attention to his own multi-millionaire status, and his wife’s $316,962 salary for ushering the poor and needy away from the University of Chicago Medical Center. Not to mention the $101,083 she received from TreeHouse Foods Inc., a subsidiary of that bastion of workers’ rights, Wal-Mart, which lifted her pay in 2006 to $374,701. And why Mr. Obama lobbied for a $1 million earmark for the Center while his wife was drawing a hefty salary there. And on and on.

Rule one in waging a gentlemanly campaign: keep off the candidate’s wife. Rule two: don’t hurl rocks if you live in a conservatory. If Mr. Obama wanted to fight by the Marquess of Queensberry’s rules, he sure has a strange way of showing it.

nwapshott@nysun.com