Disclosure of a secret Senate Republican campaign document urging that Sen. Howard M. Metzenbaum (D-Ohio) be characterized as a "communist sympathizer" drew cries of outrage yesterday from Democrats, along with apologies from Senate GOP leaders.

Sen. Rudy Boschwitz (R-Minn.), chairman of the National Republican Senatorial Committee, acknowledged that the report was "insulting and outrageous" and apologized personally to Metzenbaum in a moment of poignant drama on the Senate floor. "I apologize for all my colleagues," added Minority Leader Robert J. Dole (R-Kan.) as he crossed the Senate floor to shake Metzenbaum's hand.

The 71-page "research overview" was prepared by the Republican senatorial committee and circulated among Ohio Republicans who are preparing to challenge Metzenbaum in next year's elections. Both of his prospective opponents, Cleveland Mayor George Voinovich and Rep. Bob McEwen (R-Ohio), denounced it, and Robert Hughes, chairman of the Cuyahoga County Republican Party, said it "managed to raise political stupidity to an art form."

The document suggested strategies for attacking Metzenbaum's record, character and integrity, outlining what was described as the senator's membership in "communist causes" during the 1940s and evidence that his "communist sympathies have found their way onto the Senate floor."

As the first example of such "sympathies," the report cited a newspaper article in 1976 quoting Metzenbaum as saying that "the long-range solution for unemployment lies in creating a healthy atmosphere for industrial expansion" and as declining to rule out "use of WPA and Jobs Corps techniques as a pump primer."

The report also urged that "caution should be observed to avoid having the attack look 'McCarthyistic,' " thereby depriving Metzenbaum of an opportunity to respond by citing his patriotism. In addition, it suggested that "third-party surrogates" be used to attack his legislative record in order to "soften up Metzenbaum's negatives" in preparation for the campaign.

According to Tom Mason, director of communications for the GOP Senate committee, the report was prepared by researcher Donald W. Walter Jr. under the direction of the committee's former research director, Mark Liedl. Liedl left the post about six weeks ago in a "mutual parting of the ways" that had nothing to do with the Metzenbaum report, he said. "It was under his watch, his direction, and he is no longer with us . . . although we are all responsible," said Mason, who has taken over Liedl's duties.

Mason said the report, with a covering page dated April of this year, was begun late last year and finished in March. It was rejected as "something we did not want to put out" but was sent to Ohio anyway "by mistake," he said.

Metzenbaum denounced the report as "filled with lies, innuendos, McCarthyism and stupidity" when it was disclosed yesterday by the Cleveland Plain Dealer.

Even stronger words were employed by Metzenbaum's colleagues as the issue spilled over onto the Senate floor yesterday afternoon. Senate Majority Leader Robert C. Byrd (D-W.Va.) called it "the very definition of sleaze."

"Scurrilous . . . tawdry," said Sen. John Glenn (D-Ohio). Sen. John F. Kerry (D-Mass.), chairman of the Democratic Senatorial Campaign Committee, said it represents "the worst of modern American political strategy."

Dole called it "reprehensible," and Boschwitz said he agreed with Metzenbaum that it "has no place in politics and indeed demeans the political process."

The furor over the Metzenbaum report is the second major controversy involving the GOP senatorial campaign committee in less than a year. Before Boschwitz took over, committee officials paid themselves big bonuses even though the Republicans had just lost control of the Senate to the Democrats, prompting an outcry. Republicans also engaged last year in a voter-challenge program during the Louisiana Senate campaign that appeared to be aimed at disqualifying blacks from voting. Revelation of that program led to litigation and political embarrassment.

Boschwitz told his colleagues he had not seen the report on Metzenbaum, which he said was prepared earlier this year as he was assuming the chairmanship of the committee. But he added, "I take full responsibility for it, as I should."

Mason said another report on a Democratic senator, whom he did not identify, was "done and killed" this year without distribution. Other research reports on Democratic senators that the committee routinely does for upcoming campaigns "are not anything close" to what was prepared on Metzenbaum, he said.