It is a sorry fact of American political life that campaigns get ugly, often in their final weeks. But Senator John McCain and Gov. Sarah Palin have been running one of the most appalling campaigns we can remember.

They have gone far beyond the usual fare of quotes taken out of context and distortions of an opponent’s record — into the dark territory of race-baiting and xenophobia. Senator Barack Obama has taken some cheap shots at Mr. McCain, but there is no comparison.

Despite the occasional slip (referring to Mr. Obama’s “cronies” and calling him “that one”), Mr. McCain tried to take a higher road in Tuesday night’s presidential debate. It was hard to keep track of the number of times he referred to his audience as “my friends.” But apart from promising to buy up troubled mortgages as president, he offered no real answers for how he plans to solve the country’s deep economic crisis. He is unable or unwilling to admit that the Republican assault on regulation was to blame.

Ninety minutes of forced cordiality did not erase the dismal ugliness of his campaign in recent weeks, nor did it leave us with much hope that he would not just return to the same dismal ugliness on Wednesday.

Ms. Palin, in particular, revels in the attack. Her campaign rallies have become spectacles of anger and insult. “This is not a man who sees America as you see it and how I see America,” Ms. Palin has taken to saying.

That line follows passages in Ms. Palin’s new stump speech in which she twists Mr. Obama’s ill-advised but fleeting and long-past association with William Ayers, founder of the Weather Underground and confessed bomber. By the time she’s done, she implies that Mr. Obama is right now a close friend of Mr. Ayers — and sympathetic to the violent overthrow of the government. The Democrat, she says, “sees America, it seems, as being so imperfect that he’s palling around with terrorists who would target their own country.”

Her demagoguery has elicited some frightening, intolerable responses. A recent Washington Post report said at a rally in Florida this week a man yelled “kill him!” as Ms. Palin delivered that line and others shouted epithets at an African-American member of a TV crew.

Mr. McCain’s aides haven’t even tried to hide their cynical tactics, saying they were “going negative” in hopes of shifting attention away from the financial crisis — and by implication Mr. McCain’s stumbling response.

We certainly expected better from Mr. McCain, who once showed withering contempt for win-at-any-cost politics. He was driven out of the 2000 Republican primaries by this sort of smear, orchestrated by some of the same people who are now running his campaign.

And the tactic of guilt by association is perplexing, since Mr. McCain has his own list of political associates he would rather forget. We were disappointed to see the Obama campaign air an ad (held for just this occasion) reminding voters of Mr. McCain’s involvement in the Keating Five savings-and-loan debacle, for which he was reprimanded by the Senate. That episode at least bears on Mr. McCain’s claims to be the morally pure candidate and his argument that he alone is capable of doing away with greed, fraud and abuse.

In a way, we should not be surprised that Mr. McCain has stooped so low, since the debate showed once again that he has little else to talk about. He long ago abandoned his signature issues of immigration reform and global warming; his talk of “victory” in Iraq has little to offer a war-weary nation; and his Reagan-inspired ideology of starving government and shredding regulation lies in tatters on Wall Street.

But surely, Mr. McCain and his team can come up with a better answer to that problem than inciting more division, anger and hatred.