Two days after Patrick Buchanan announced his challenge to President Bush, the nation's leading conservative voice, William F. Buckley Jr., has called on Buchanan to renounce past statements that Buckley, among many others, deems antisemitic.

Buckley's reservations about Buchanan emerge in a long and nuanced meditation on antisemitism published in the latest National Review, which just last week declined to endorse his insurgent candidacy on other grounds. The extraordinary 40,000-word essay on antisemitism occupies all but nine pages of the Dec. 30 issue, which has just been sent to subscribers.

Buchanan, who has weathered charges of antisemitism before, was criticized sharply after he made televised remarks last winter referring to "only two groups that are beating the drums for war in the Middle East -- the Israeli defense ministry and its amen corner in the United States." Not long afterward, he referred to the U.S. Congress as "Israeli-occupied" territory.

These remarks alone, Buckley writes in one of his four case studies in contemporary antisemitism, can be excused as legitimate hyperbole for an opponent of intervention in the Persian Gulf, as Buchanan was. But Buckley finds damning Buchanan's subsequent naming of four people in Israel's putative "amen corner" during the buildup to the invasion: Henry Kissinger, columnists A.M. Rosenthal and Charles Krauthammer, and former defense official Richard Perle.

"They have in common many things," says Buckley of the four. "The most conspicuous of these is that they are Jewish." Why, Buckley asks, did Buchanan not select the equally hawkish Alexander Haig, James J. Kilpatrick, George Will and Frank Gaffney? "Four Christians," Buckley notes.

As for another Buchanan comment, a prediction about who would do the fighting in the war he opposed -- "kids with names like McAllister, Murphy, Gonzalez and Leroy Brown" -- Buckley says "there is no way to read that sentence without concluding that Pat Buchanan was suggesting that American Jews manage to avoid personal military exposure even while advancing military policies they (uniquely?) engineer."

Buchanan's presidential campaign did not respond yesterday to requests for comment.

Charges of antisemitism have been a burden historically for the American right, and Buckley has worked hard through the National Review to separate mainstream conservatism from that stigma. To the degree that conservative voters share his convictions, Buckley's essay will be consequential for Buchanan's presidential candidacy.

Buckley said yesterday that he had written the essay long before Buchanan's presidential intentions became public, and had not changed it because of the campaign except to object, in a footnote, to unflattering comparisons in the press between Buchanan and David Duke.

"I'm in favor of 95 percent of what he's doing and saying," Buckley said in an interview. "We think a protest movement {against Bush} is desirable. On the other hand we think it's incorrect to say that Patrick Buchanan has, as of this moment, a Delphic right to describe the dimensions of conservatism when he's carrying this much baggage: ... protectionism, nativism and isolationism, plus his additional insensitivity on this particular issue {antisemitism}, which he's never backed off from. I hope he changes his mind, and then proceeds to do it."

Buckley added: "If you ask, do I think Pat Buchanan is an antisemite, my answer is, he is not one. But I think he's said some antisemitic things."

In the essay, Buckley is discernibly tougher: "I find it impossible to defend Pat Buchanan against the charge that what he did and said during the period under examination amounted to anti-Semitism, whatever it was that drove him to say and do it; most probably an iconoclastic temperament."

The detailed consideration of Buchanan and his critics is only the second of four sections that, for Buckley, illuminate the changed state of antisemitism in American public life as the nation leaves the "shadow" of the Holocaust.

His first case is Joseph Sobran, the columnist (and longtime Buckley protege) who was slowly and painfully separated from the inner councils of the National Review as he refused to soften his hard-line -- and in some eyes antisemitic -- writings about Israel.

His third subject is the Dartmouth Review, the conservative undergraduate journal most recently in the news for printing a line from "Mein Kampf" on its masthead -- a controversy most notable for what Buckley says are the excesses of those, including the president of Dartmouth, who responded with a campaign of "anti-anti-Semitism," in Buckley's phrase.

And his fourth subject is the Nation, the old-line liberal journal that has published what Buckley considers to be the "genuinely and intentionally and derisively anti-Semitic" views of Gore Vidal, the novelist and essayist. For the American right -- "short of the real fever swamps" -- Buckley said yesterday, antisemitism is "pretty much a non-problem. On the left, it's a creeping problem."

Even so, the non-problem has consumed the 66-year-old father of the postwar conservative movement in recent years, and he decided last summer, he said, that a grand overview was in order. Yesterday Buckley described his effort in characteristic language and thinking: "It's a useful a posteriori exercise; i.e., I take four episodes and ask, 'What can we learn about this that is generally useful,' and I explore them with that in mind, rather than attempting a priori to say 'antisemitism is X, Y and Z and we will now extrude all the refinements on that proposition.' "

When asked what it was he had learned from the exercise, Buckley returned to his brother conservative Buchanan and paraphrased a paragraph from his essay.

Buchanan survived the storm that followed his provocative remarks, Buckley writes. "He would not have done so, in my opinion, 10 years ago; which is why I speak of Auschwitz having become a senior citizen, fading away as the dynamic arbiter of the nation's moral reflexes. This development is welcome in one sense, unwelcome in another. If it intimates a creeping cultural-political insensibility to antisemitism, then it is both wrong and alarming. If it suggests only that the public feels free to react against intimidation on the subject of Israel, then it is healthy."

The essay, appearing at the outset of the presidential campaign, is likely to churn a subject that has often roiled the opinion magazines and op-ed pages of the land. Recapitulating the controversies of the last decade, Buckley quotes at length -- and with frequent bracketed interjections -- from the writings of Rosenthal, Michael Kinsley, David Frum, Robert Novak, Fred Barnes, Joshua Muravchik, Eric Alterman, Irving Kristol, Norman Podhoretz, Martin Peretz, Edwin M. Yoder Jr., Leslie Gelb and Richard Cohen, among others.

All of them, and the principals in the Buckley essay, may be counted on to weigh in once they've read the article. Among the few who have early copies, Rosenthal had not read it and was leaving the country, and Podhoretz was reserving comment for his own written response.

Another early reader, Sobran, also intends to reply to Buckley in a subsequent issue of the National Review. He said yesterday that the essay "wasn't an attack on me" or on Buchanan. "He's not trying to smear us, but we have been smeared, by others ... there have been efforts to ruin our careers by these damaging attacks."

The charge of antisemitism, Sobran said, "has become a cynical maneuver on the part of a lot of Israel's supporters. ... Neither Pat nor I advocates treating Jews the way Jews treat non-Jews in Israel -- making them second-class citizens, let alone persecuting them. But we don't have a word for the corresponding prejudice against non-Jews."

Antisemitism, Sobran said, is a word that has "the status of a curse. It doesn't belong in a rational dialectical universe."