It's hard to believe, I know, but the McCain campaign seems intent on delving further and further into the gutter in its desperate attempt to tar Barack Obama with something - anything - that will undermine the trust he's earned from voters for the past two years. The most recent episode involves a full-court press in speeches and interviews by both candidates and their surrogates to inspire yet another McCarthyite panic, this one among Jews (especially those in Florida, no doubt).

To review, five years ago Barack Obama spoke at the same dinner as Rashid Khalidi, a noted scholar and current professor at Columbia University. There were some harsh things said by others at the dinner, but not by Khalidi or Obama. Obama "called for finding common ground" in his remarks and said that his commitment to Israel's security is "nonnegotiable", according to the Los Angeles Times, which wrote an extensive account of the dinner six months ago. The reporter, Peter Wallsten, based that story on a videotape of the dinner, which was provided to him by a source on the condition that it not be released.

Now right-wingers are demanding that the tape be released. "A major news organisation is intentionally suppressing information that could provide a clearer link between Barack Obama and Rashid Khalidi," said McCain campaign spokesman Michael Goldfarb. "The election is one week away, and it's unfortunate that the press so obviously favours Barack Obama that this campaign must publicly request that the Los Angeles Times do its job - make information public." Sarah Palin, on the stump in Ohio on Wednesday, said: "Among other things, Israel was described there as the perpetrator of terrorism rather than the victim. What we don't know is how Barack Obama responded to these slurs on a country that he professes to support." (Note: professes to support).

McCain, sans any evidence whatsoever, claims that, hey, maybe William Ayers was there too. He told Larry King on Wednesday: "I still think, you know, we're watching now, a major newspaper has a tape that apparently has Mr William Ayers in it. I don't know if it does or not. That's the allegation. But that newspaper and their parent, the Tribune Company, and the Obama campaign refuse to release that. Shouldn't the American people know about that? At least they should have full information." There's even a protest outside the LA Times.

This pathetic effort should, in a normal world, be laughed off the airwaves and news pages. First and most importantly, Khalidi is not someone that anyone should be ashamed to know. He is a noted and well-respected Palestinian scholar. Michael Hudson, director of the Centre for Contemporary Arab Studies at Georgetown, describes Khalidi as pre-eminent in his field, a courageous scholar and public figure. John McCain apparently thought so too at one point, since the International Republican Institute, with McCain at the helm, gave Khalidi's Centre for Palestine Research and Studies a $448,000 grant in the late 1990s.

No concrete offence of Khalidi's has actually been alleged, so far as I'm aware, except that he once served as spokesman for the PLO, which Khalidi denies. Still, McCain made this stunning comparison on Wednesday: "If there was a tape of John McCain in a neo-Nazi outfit, I think the treatment of the issue would be slightly different," he said in an interview with Hispanic radio stations.

This modern-day McCarthyism seems to rely much more on the fact that Rashid Khalidi's name is Rashid Khalidi than any concrete allegations of wrongdoing. And the haphazard insinuation that maybe Ayers was there too is a transparent attempt to bait the Times into releasing the tape. The McCain people must know that a journalist cannot and will not burn a source. "The Los Angeles Times did not publish the videotape because it was provided to us by a confidential source who did so on the condition that we not release it," said the newspaper's editor, Russ Stanton. "The Times keeps its promises to sources."

Perhaps Sarah Palin is actually ignorant enough about journalism to believe the foolish charge she utters when complaining: "It must be nice for a candidate to have major news organisations looking out for their best interests like that. Politicians would love to have a pet newspaper of their very own." But surely Goldfarb, who left the Weekly Standard to join McCain's campaign, knows better, and is playing the dim bulb for purely political purposes. (All this will no doubt keep him in good standing with his colleagues at the Standard, alas.)

Sadly, the media has been more than happy to provide that noise. "Sen John McCain … continued to criticize the radical professors with whom Sen Barack Obama … has associations," explained ABC's Jake Tapper, simply assuming that Khalidi fit this description without any apparent familiarity with his work. "McCain attacked Obama for associating with both William Ayers and Rashid Khalidi on CNN's Larry King Live tonight."

In King's conversation with McCain, he too, bought into the crazy notion that the LA Times was somehow suppressing the news that the newspaper, alone, had reported. Last night on CNN, Anderson Cooper summed up the MSM attitude perfectly: "McCain and Palin are making a big deal about this Palestinian-American professor. We don't take sides on this programme. We just want the facts, so we asked Tom Foreman to look into this guy and allegations of a relationship with Obama and McCain."

A long package ensued. The only sensible perspective provided by CNN last night was this, from Dana Bash: "When I asked the McCain aide why they are just now bringing up a six-month-old article about a dinner five years ago, the aide was strikingly candid. He said - quote - 'Because Obama may be one week away from being elected president.'"

Really, one shudders for the fate of the free world when one considers the combination of stupidity, tastelessness, bigotry and outright idiocy that lies at the centre of this appeal.