WASHINGTON (AP) _ A memo to Attorney General Edwin Meese III from his friend E. Robert Wallach broached a proposal to bolster Israel's moderate Labor Party against the rival Likud bloc.

In his September 1985 memo, made public Monday, Wallach stressed the need to encourage Soviet leaders to allow greater Jewish emigration to Israel because Russian Jews, once they are voters in Israel, tend to support the Labor Party.

Israel contends that 400,000 Jews want to emigrate from the Soviet Union - enough to make a difference in an Israeli election, if all were allowed to resettle in Israel.

Wallach's idea was based on the assumption that Israel would call early elections no later than March 1986, but it is unclear whether an influx of Russian Jews could have brought about a Labor victory. No election was held, and in October 1986, then-Prime Minister Shimon Peres switched jobs with Foreign Minister Yitzhak Shamir in a power-sharing arrangement.

''There is a need to provide Israel with a increasing flow of Ashkenazi Jews to help balance the influx of Sephardic-Oriental Jews who have a natural affinity and affiliation with Likud,'' Wallach wrote.

''From the standpoint of American interests, the advantage is evident,'' he added without elaboration.

Ashkenazi Jews are those whose origins are in Europe, while Sephardic Jews came from Asia and Africa. Voter breakdown shows that Sephardim, who constitute some 60 percent of Israel's 3.5 million Jewish population, tend to support Likud more than they do Labor.

U.S. leaders in the past have said privately they feel more comfortable with Labor, which exhibits greater willingness to cede lands to Israel's Arab neighbors in return for a peace settlement. Likud is more hardline, refusing any territorial concessions.

But publicly, the United States has consistently veered away from taking any stand that could be viewed as interference in internal Israeli politics.

The Wallach-Meese memo is the focal point of a criminal investigation of the attorney general. At issue is whether Meese knew, from reading the memo, of a plan to pay a bribe to the Labor Party, and, if so, why he did nothing about it.

Wallach wrote that his business associate, Israeli-born oilman Bruce Rappaport, had commissioned several public opinion polls that indicated a ''high probability'' of early elections and growing support for Labor.

Rappaport, who resides in Switzerland and is a generous contributor to the Labor Party, confirmed an arrangement with Peres that Israel would receive some $700 million over 10 years from the pipeline that would pass near the Israeli border on its way from Iraq to the Red Sea port of Aqaba.

''What was also indicated to me ... is that a portion of those fund will go directly to Labor,'' Wallach wrote.

The emigration issue, as outlined by Wallach, revolves around Soviet leader Mikhail Gorbachev's promise to Peres to consider increasing emigration levels if the Jews went directly to Israel rather than to the United States, Wallach said.

The United States has refused to take any stand in support of direct Soviet emigration to Israel, saying it was up to the Jews to decide where they want to live.