Patrick J. Buchanan, who is expected to announce his candidacy for the Republican presidential nomination Tuesday, yesterday assailed President Bush for abandoning "conservative principles" and made clear he would not be reluctant to use issues associated with former Ku Klux Klan leader David Duke.

"I'm not going to walk away from my views simply because David Duke takes them," Buchanan said on ABC's "This Week With David Brinkley."

Duke, a onetime neo-Nazi who is also challenging Bush in the Republican primaries, "comes out of another tradition, to put it mildly," Buchanan said, but he added that racial quotas and immigration are "valid conservative issues."

"I think God made all people good, but if we had to take a million immigrants in, say Zulus, next year, or Englishmen, and put them in Virginia, what group would be easier to assimilate and would cause less problems for the people of Virginia?" Buchanan asked.

Virginia Gov. L. Douglas Wilder (D), campaigning last night in Arkansas, said: "I can't believe that. It's shocking and sad, but it doesn't surprise me in terms of the mood I've seen in the country in the last several months. That's why I've said the message of David Duke is out there."

Wilder called Buchanan's remark "hyperbole at its highest. That appeal is more obvious than I would have expected though."

Buchanan asserted in the televised interview that "there is nothing wrong with us sitting down and arguing that issue that we are a European country, {an} English-speaking country."

Buchanan, who has worked for two presidents, recast himself as the tribune of revenge against "the professional political class in this city" and said politicians "have double-crossed the American people."

"Mr. Bush is not in trouble because of Pat Buchanan," he asserted, but because he "promised not to raise taxes and raised them. . . . He said he wouldn't sign a quota bill and then signed it." Buchanan said a president could make Congress agree to budget cuts by declaring his willingness to "shut down this government from November to January."

During the televised interview, Buchanan was called to account not only for his current views, but also for a lifetime of commentary.

Buchanan vigorously reasserted his oft-expressed opposition to Bush's gulf war policies. "I didn't think that worthless emir, excuse me, was worth a single American Marine," Buchanan said. "Iraq had not attacked my country." The major regional threat, he said, is Iran.

Buchanan also defended his championing of the cause of John Demjanjuk, accused of being "Ivan the Terrible" at the Nazi death camp of Treblinka. "John Demjanjuk is not the man," Buchanan said. "There are 20 affidavits now in Israeli court which confirm what I've been arguing for 10 years."

Buchanan had once asserted that hundreds of thousands at Treblinka could not have been killed by diesel engine exhaust fed into the gas chambers because they "do not emit enough carbon monoxide to kill anybody." Yesterday he said: "What happened at Treblinka was . . . a hell on Earth. Jews were brought there in the hundreds of thousands and died in the thousands."

Columnist George Will pressed Buchanan: "You just said they came there in the hundreds of thousands and died in the thousands. Are you denying that hundreds of thousands of Jews died at Treblinka?"

"No, no, I certainly cannot deny that," Buchanan said. As for his comments on diesel engines, Buchanan replied: "Look, you're getting into a technical question."

Staff writer Donald P. Baker in Arkansas contributed to this report.