More than three weeks ago, I outed Patrick Buchanan, the former senior White House official in the Nixon and Reagan administrations, erstwhile candidate for the Republican presidential nomination and now a highly paid political commentator on MSNBC, for sponsoring a Holocaust denial forum on his Web site. Within hours of this disclosure in a New York Daily News article, the forum in question, entitled "Disinformation, Deception and Other Tricks: Discussion About 'The Holocaust'" (with The Holocaust in quotes, of course), mysteriously vanished from Buchanan.org and the link to it was disabled. The Buchanan Web site's forum followed the standard Holocaust deniers' playbook, complete with such gems as "Most historians believe it was logistically impossible to gas 6 million Jews and reduce their bodies to ashes"; "We have known for some time that the Auschwitz myth is of an exclusively Jewish origin"; "The same blinded people that believe that the Germans intentionally killed Jews - also believe the myth of the Anne Frank diary"; and "Rightly or wrongly - the Jew was blamed for a lot of the problems that Germany suffered. The Jews were given years of warnings that they were unwelcome in Germany. A lot of Jews fled Germany in the late 1930s. The United States was not very anxious to accept very many. This was when white Christians still had a little control of our nation." ONE MIGHT have expected the disclosure of this forum to at least raise some eyebrows at MSNBC. After all, two years ago the news channel summarily fired talk show host Don Imus for making a racially insensitive remark about the Rutgers University women's basketball team. Sponsoring a Holocaust denial forum on one's Web site strikes me as no less offensive. But not a single MSNBC executive has deigned to publicly address Buchanan's association with anti-Semites, white supremacists and other assorted bigots. Since Buchanan's Holocaust denial forum became public, he has appeared repeatedly on at least three MSNBC programs: Morning Joe, Hardball with Chris Matthews and Andrea Mitchell Reports. Neither Joe Scarborough nor Mika Brzezinski, the cohosts of Morning Joe, asked Buchanan to explain why he provided a platform for Holocaust deniers. Chris Matthews did not ask Buchanan whether he approved of or agreed with the Holocaust denying screeds that were posted on Buchanan.org. Andrea Mitchell did not ask Buchanan how and why the Holocaust denial forum was so suddenly removed from his Web site. Matthews would never have remained silent in the face of slurs directed at Irish-Americans, or Scarborough at Southern conservative Christians, or Brzezinski at Polish Catholics, or Mitchell at women. Holocaust denial by definition is toxic, and Buchanan's MSNBC colleagues have an obligation to confront him on their shows with the vitriol he allowed to be disseminated under his auspices. MSNBC'S AUDIENCES for the most part have no idea that Buchanan is not just another affable, well-spoken if arch-conservative pundit. They do not know that he has compared John Demjanjuk, the Nazi guard at the death camps of Sobibor and Majdanek who has just been deported from the US to stand trial in Germany, to Jesus Christ. They do not know that he wrote in his March 17, 1990, syndicated column that Jews could not have been murdered in the gas chambers of Treblinka, and dismissed the Holocaust survivors' experiences as "group fantasies of martyrdom and heroics." They do not know that Buchanan has referred to Capitol Hill as "Israeli-occupied territory" and called Israel "a strategic albatross draped around the neck of the United States." They do not know that he told the Christian Coalition in 1993 that "our culture is superior. Our culture is superior because our religion is Christianity and that is the truth that makes men free." They do not know that Buchanan has actively lobbied on behalf of Nazi war criminals like Demjanjuk, Karl Linnas and Arthur Rudolph. They do not know that he called for the abolishment of the US Justice Department's Office of Special Investigations, which prosecutes and seeks to deport Nazi war criminals from the United States, because he considered the unit to be "a shark force... running down 70-year-old camp guards." They do not know that he once wrote that "though Hitler was indeed racist and anti-Semitic to the core, a man who without compunction could commit murder and genocide, he was also an individual of great courage, a soldier's soldier... a political organizer of the first rank, a leader steeped in the history of Europe, who possessed oratorical powers that could awe even those who despised him." Patrick Buchanan has no greater credibility or respectability than David Duke, the former imperial wizard of the Ku Klux Klan, or Louis Farrakhan, the grotesquely anti-Semitic leader of the Nation of Islam. That is why the American Gathering of Jewish Holocaust Survivors and Their Descendants is calling on Holocaust survivors, members of their families and the Jewish community as a whole to write to MSNBC president Phil Griffin to express their collective outrage. If MSNBC's executives insist on retaining Buchanan as a fixture on their news channel, he must be clearly identified as an enabler of Holocaust deniers and a defender of Nazi war criminals whenever he appears on the air. The writer is vice president of the American Gathering of Jewish Holocaust Survivors and Their Descendants, general counsel of the World Jewish Congress and adjunct professor of law at Cornell Law School.