Nothing in the presidential campaign so far has been as instructive as its swift descent into the politics of personal destruction. Although voters have probably heard little lately that they did not already know about Sen. Barack Obama, they have learned something very important about Sen. John McCain.

Back when this contest began, McCain expressed the desire for a different kind of campaign than we have seen in recent years. Rather than the old style of character-assassination politics perfected by his former nemesis Karl Rove to defeat him, Al Gore and John Kerry, the Arizona Republican urged a substantive debate and a fair comparison of public careers. He invited Mr. Obama to join him in a series of town hall meetings to discuss their competing visions of the nation's future. He hoped to run "a respectful campaign focused on the issues and values that are important to the American people."

That is what the man known for straight talk said he wanted. But it is no longer possible to assume that he meant it, even then. Now that he is losing, he has sunk into the same shameful conduct that he once professed to despise.

Entering the election's final weeks, the rhetoric of the former maverick and his lipstick-toting pit bull, Gov. Sarah Palin, has turned so ugly and inflammatory that their rallies have begun to sound like lynch mobs.

"Who is the real Barack Obama?" asked McCain at a rally in New Mexico — and didn't correct a thug who yelled, "Terrorist!" in response. "Kill him!" screamed the crowd at a rally in Florida after Ms. Palin smeared Mr. Obama for his supposed association with former Weather Underground bomber Bill Ayers. She didn't object to the lynching cry, but went on to say: "I'm afraid [Obama] is someone who sees America as 'imperfect enough' to work with a former domestic terrorist who had targeted his own country."

Sen. Joseph Lieberman, the McCain surrogate from Connecticut, assures us that this is "all fair game," a statement that would be surprising if it were not uttered by him. He was happy to accept Obama's support when his own reelection was in jeopardy two years ago, and he is happy to help smear him today.

But is it fair game? Considering that Obama was a child when Mr. Ayers was involved in those bombings, and that he has forthrightly condemned the Weather Underground's lethally insane conduct, it is neither fair nor germane.

It is somewhat less fair, for instance, than dredging up McCain's old association with an international fascist outfit called the World Anti-Communist League. Back when he joined up with WACL, a quarter-century ago, the shadowy group was a haven for war criminals, drug smugglers and other miscreants from Europe, Latin America, Asia and the Mideast, promoting the ideology of the far right, supposedly to combat the Soviet foe. Among those involved in WACL were the fascist terrorists identified as responsible for bombings in Italy that had killed hundreds of innocent people.

Was McCain, then a political neophyte, responsible for the crimes of his associates in WACL? No, but he was an adult when he signed up, and he lent his prestige to them. He says he quit, but John Singlaub, the ultra-right former Army general who served as WACL's American frontman for many years, doesn't recall him resigning.

Then there is McCain's former association with financial crook Charles Keating, who was not only a political supporter but a benefactor who brought Cindy McCain into his investments and bestowed free Caribbean vacations on the McCain family. Is it fair to revisit that old controversy, which the senator thinks he has expiated? Only because his campaign wants to distract the public with discussions of "character."

What these concluding weeks have told us about the Republican candidate, to the shock and surprise of many of his admirers, is that he misunderstands the meaning of honor. Evidently he believes that the credit he accrued for suffering bravely for his country in Vietnam somehow licenses him to campaign as crudely and deceptively as he can, if that will help him to win. He seems not to realize that the respect he earned so many years ago requires him to uphold a higher standard of decency in politics.

A leader who doesn't realize that honor can be lost as well as earned is a danger to himself and his country.

Joe Conason writes for the New York Observer (www.observer.com). To find out more about Joe Conason, visit the Creators Syndicate website at www.creators.com.

COPYRIGHT 2008 CREATORS SYNDICATE, INC.