Taking dead aim at Republican presidential candidates who oppose affirmative action, Jack Kemp yesterday said his party will "find it very hard to govern the country if it runs a campaign that separates people by race and by gender."

The former secretary of housing and urban development, who took himself out of the 1996 race earlier this year, told reporters he was determined to use his influence to see that the GOP runs on tax reform and economic issues "rather than on reducing immigration by one-third or stopping affirmative action."

"If '96 is run on dividing the races, I will not participate," he said.

Kemp's comments broke the near-solid Republican opposition to affirmative action programs and gave President Clinton -- who defended those programs earlier this week -- his first prominent GOP supporter on that issue.

The former Buffalo representative and 1988 contender for the Republican presidential nomination said he would have voted against the position taken Thursday by California Gov. Pete Wilson (R) when Wilson led the majority of University of California regents in ending minority preferences in university hiring and admissions.

"I am opposed to that," Kemp said. "I think race is a legitimate factor to take into consideration." Kemp predicted that "I'm going to get my head whacked" for his position -- and Wilson was not long in reacting.

In a statement from Sacramento, the governor said, "This is the second time in recent months Jack has sent unsolicited advice to Californians from his seat of wisdom in Washington. . . . I would urge Jack to . . . come down in favor of fairness to deserving individuals of all races -- not favoritism to a preferred racial group."

In addition to Wilson, Senate Majority Leader Robert J. Dole (R-Kan.), Sen. Phil Gramm (R-Tex.), commentator Patrick J. Buchanan, and almost all the other GOP presidential contenders have vowed to end federal affirmative action programs. Sen. Arlen Specter (R-Pa.) has called affirmative action "a wedge issue," but has not said whether he would continue the programs.

Kemp argued that it was "legitimate" for Republicans to examine the effectiveness and equity of existing programs designed to aid women and minorities for past discrimination, "but it's putting the cart before the horse . . . to throw out all affirmative action without any idea of what is going to replace it."

Kemp also criticized his successor in the House, Rep. Bill Paxon (R-N.Y.), the chairman of the National Republican Congressional Committee, for a committee flier containing the photos of "targeted" Democratic incumbents, most of whom were women, African Americans or Jews. "I don't like campaigns putting someone's picture up, whether it's Willie Horton or Dan Rostenkowski," Kemp said. "I wouldn't do it." Paxon maintained that the Democrats were chosen solely on the basis of their voting records.

Referring to the congressional hearings on the federal raid on the Branch Davidian compound, Kemp cautioned his fellow Republicans to be "very careful on attacking law enforcement officers. No one was more critical of Waco than Jack Kemp," he said, "but my party should be very careful of spreading fear about people who protect our lives, notwithstanding that they sometimes overstep the bounds."

Yesterday's remarks continue a pattern of deviations from conservative orthodoxy by the man who was the favorite in a poll of 1992 convention delegates for the 1996 nomination. Last fall, he angered Wilson by opposing the Wilson-backed Proposition 187, a measure that denied virtually all health, education and welfare benefits to illegal aliens and their children.

Kemp heads a commission, appointed by Dole and House Speaker Newt Gingrich (R-Ga.), to propose a major tax reform. He said the panel's report, due before year's end, would call for reducing the top tax rate to less than 25 percent and coming as close as possible to the Hong Kong code, which he said taxes incomes and corporate profits at 15 or 16 percent and has no tax on capital gains. "If I could impose that tax in Washington, D.C.," he said, "it would be another Hong Kong in five years."

Kemp said he hoped that "tax reform and rate reduction will be at the center of the Republican message in 1996. If not, 1996 will be nastier and meaner and more ad hominem, with the focus on issues like Proposition 187 or affirmative action."