Here's one of the toughest critiques of Patrick Buchanan THE SCRAPBOOK has read of late, and get this: It comes not from George W. Bush or any of the Republican candidates, but from inside the Buchanan campaign, from a "senior policy adviser." Here are some excerpts of what this adviser has written:

"There have been Buchanan references to 'group fantasies of martyrdom and heroics' among Holocaust survivors, and columns about how diesel fumes could not have killed hundreds of thousands of Jews at Treblinka. Needless to say, such assertions are offensive to Jews, to friends of Jews, and all others who believe that respect for historical truth is an important feature of civilized society. . . .

"I find it unlikely that Buchanan doesn't understand what he's doing with such musings. No matter how sporadically he writes such things, they confer upon Buchanan a strangeness that makes it utterly impossible to take him seriously as a presidential candidate.

"The conservative National Review treats Buchanan's campaign with deference and respect. [It] expresses the hope that he will become more Reagan-like. . . . For me, it's far too late. Buchanan has spent too much energy denouncing neo-conservatives as 'ideological vagrants'; his Holocaust stuff is far too weird. Pat for President? It's not even worth discussing."

Hmmm. A plant in the Buchanan camp? No. These criticisms are actually from a February 1992 column by Scott McConnell. The same Mr. McConnell who announced in his New York Press column last week that he was departing journalism for the Buchanan campaign. It has offered him a job as senior policy adviser and he has "jumped at the chance." After all, he writes, "the chance to be part of such an enterprise, which could have a huge and lasting impact on the American political system, is one of the greatest privileges I can imagine."

To paraphrase the eminent political analyst Ricky Ricardo, somebody's got some 'splaining to do.