A private memo drafted for conservative Republican senators by their staffers warns that if Majority Leader Robert J. Dole forces a pre-election vote on the long-delayed genocide treaty, which he made the Senate's pending business yesterday, it could cost the party Senate control.

Such forebodings about the consequences of a treaty awaiting ratification since 1949 without seizing the nation's imagination one way or another sound exaggerated. But the post-World War II agreement to outlaw mass extermination of populations always has excited intense, though limited, passions. Intended to prevent the recurrence of the Jewish Holocaust, the treaty has been blocked from Senate ratification for 36 years by right-wing concerns over ceding national sovereignty to the World Court.

Apart from ideology, national GOP operatives are as unhappy with Dole's desire for a vote as are his right-wing colleagues. If Republican senators vote for it, they lose heavily with conservatives; if they vote against it, they may lose Jewish backers and their campaign contributions. An informal poll of 18 Republican incumbents seeking reelection shows only Sen. Slade Gorton of Washington privately pushing for a chance to vote on the treaty this year.

The memo by staffers for right-wing senators suggests the majority leader's timing could be more influenced by his 1988 presidential aspirations than what happens next November to his colleagues in Wisconsin, Oklahoma, Florida, South Dakota and perhaps Idaho: "Dole seems willing to jeopardize several Republican senators in tight races to enhance his presidential prospects."

Dole's answer, given to us by an aide, is that President Reagan wants the treaty and wants it now. Indeed, Reagan called for ratification in 1984, when then-majority leader Howard Baker succumbed to a threatened right-wing filibuster. But the president seldom talks about the issue, and some White House aides believe Dole could be tempting political folly.

Considering these misgivings, the genocide treaty at first glance scarcely demands an immediate Senate vote. But the American Jewish community, including thousands of voters who themselves barely escaped genocide at the hands of Hitler's Nazis, wants action now after four decades of delay. Dole has delivered two eloquent pledges to get an early Senate vote. His first commitment was made at the groundbreaking ceremony for the Holocaust Memorial Museum here last Oct. 16. He repeated his pledge a few weeks later in a speech to the Council of Jewish Federations.

"Those speeches were a commitment that he wants to keep," a national Jewish leader told us. "If Dole goes for '88, the Jewish vote is not unimportant to him, and he knows it." Indeed, Dole gave himself and his party strong new claims to Jewish support with the decision to kill the Jordan arms package two weeks ago.

But he is also working hard on the right. His letter to Secretary of State George Shultz advocating weapons for Angolan freedom-fighter Jonas Savimbi that could deal with Soviet tanks and attack helicopters was widely perceived as an overture to the Republican right wing. So, Dole has been trying to neutralize the right on the genocide treaty. He has reduced to a mere handful the original number of conservative Republicans running for reelection who formally signed a "hold" letter to him asking a delay on the treaty until after the election. Their leader, Sen. Jesse Helms (who is not up), still opposes the treaty, but has agreed not to filibuster it. But that does not help the situation in a half-dozen states where conservative Republicans won original election to the Senate with the help of their strong ideological bonds tothe right.

Such a state is Wisconsin, where conservative Sen. Robert Kasten has vigorous Jewish support and would be hard put to vote against the treaty. In South Dakota, if Sen. James Abdnor is pressured into voting for the treaty, his chances of making it even into the November election would decline; one national campaign operative told us Abdnor's all-but-certain primary opponent, Gov. William Janklow, "would kill him" with the issue.

Requiring embattled colleagues to take a stand now on the genocide treaty may signify nothing more than Dole's abiding emotional commitment to the issue, reinforced by the president's support. But practical Republican politicians cannot help but wonder why a treaty lodged in a committee pigeonhole for 40 years has to be squeezed through a time space as narrow as eight months.