"Either we get civil rights or we emigrate," was the proclamation of Jewish intellectual Max Mandelstam of Kiev, referring to the millions of his fellow Russian Jews haunted by poverty and persecution. "Our human dignity is being tramped upon . . . . Either we get decent human rights or else let us go wherever our eyes may lead us."

That was in 1882. Between then and 1920, 2 million Russian and Polish Jews took his advice and, in one of the monumental movements of people in modern times, fled the centuries of pogroms in those unforgiving lands for America, the nation of opportunity.

The children and grandchildren of these refugees now make up the great majority of the American Jewish community, and tens of thousands of them are expected to take part in a demonstration here today repeating Mandelstam's 105-year-old demands, this time to Mikhail Gorbachev, the new leader of the homeland that their ancestors left generations ago.

Organizers of today's rally, the widest coalition of American Jewish groups in memory, say the call to demonstrate has prompted unprecedented unanimity on the issue of Soviet Jewry among the approximately 6 million American Jews. Underlying that community's cohesion and recent interest on the subject, Jewish activists say, is a sense of its own Eastern European roots and a resolve to help European Jews who survived the Holocaust, in which 6 million died.

David Harris, coordinator of today's demonstration, said that many American Jews, reflecting on the Nazi extermination and seven decades of Soviet repression of Judaism, conclude, "There but for the grace of God go I . . . . For many American Jews, the opportunity to save another Jew is compelling and irresistible . . . . In the Soviet Union, there's a danger of spiritual extinction."

"For American Jews, there's a sense of belonging to this issue," said Ruth Newman, who, as executive director of the Washington Committee for Soviet Jewry, is promoting the rally among the Washington area's 170,000 Jews. "There's a sense of identification, of going back to the roots of where they came from. They read about the 'refuseniks' and they recognize the names of their grandparents."

Some Jewish leaders have compared the surge in American Jews' interest in the issue to the enthusiasm of many black Americans, starting several years ago, for the antiapartheid movement in South Africa.

Rally organizers decline to guess how many people will join in today's rally, except to say it will be in the tens of thousands. The nation's largest Jewish rallies occur in New York each May, when several hundred thousand gather in support of Soviet Jewry. This one is expected to be much smaller, because of the cold and because fewer Jews live here.

But Jewish organizers say many "grass-roots" Jews who never before have carried placards in pro-Soviet Jewry rallies, or even been members of Jewish groups, will be taking part today, including some who are traveling long distances.

"To a person, they have never marched before and aren't active in any Jewish organization," said Hinda Beral, a Jewish activist from Orange County, Calif., of the 40 people traveling the 3,000 miles from her community to the rally. "They really have gotten caught up in this issue . . . . I've never seen anything like the response on this issue."

The pro-Soviet Jewry movement has been active for at least 15 years, since about the time Soviet Jews started agitating to emigrate from the Soviet Union. Some historians see in this movement, and in American Jews' activities to aid Israel, a new secular forum for Jewish community cohesion, replacing for many Jews the strict religious practices of former generations, such as keeping kosher.

Author Charles E. Silberman, in a 1985 book about American Jews called "A Certain People," said that Jewish activities for Israel and Soviet Jewry comprise "new forms" of Jewish collective life that are "likely to transform as well as strengthen American Judaism."

Rally organizers think that one reason for the interest in this demonstration is the belief that, because of Gorbachev's commitment to glasnost or openness, the Soviet government could be on the verge of a historic loosening of restrictions on Jewish religious life there, as well as increasing Jewish emigration.

While the Soviets have released a number of well-known refuseniks in the last two years, they still are stalling up to 40,000 others who have applied to leave. The numbers of those released have gone up and down according to the state of relations between the United States and the Soviet Union. The high was in 1979, after years of warming relations, when 51,000 were released.

But that year, the Soviets invaded Afghanistan, and President Carter's angry response prompted a sharp drop over the next several years.

Only 900 were released last year, but this year, amid arms negotiations and a Soviet desire to appear accommodating, 7,000 have been allowed to emigrate.

The Soviets, placing Jews in a special category, allowed these releases even as they denied emigration to many other groups, which has stirred up anti-Jewish feeling among many Soviet citizens.

Jews waiting for release say they feel the official and unofficial anti-Semitism the moment they apply for emigration. Most are fired from their jobs and shunned by friends, and many are watched by the secret police. It's only the latest chapter in 70 years of almost uninterrupted Soviet harassment of Jews attached to their Jewishness.

Even though many Jews took part in the Bolshevik revolution in 1917 and its aftermath, anti-Semitic groups in the government and the society at large have remained suspicious of them. For decades, code words in the press and official statements, referring to Jews variously as "bourgeois," "rootless cosmopolitans" and "Zionists," have stirred popular distrust against them.

Joseph Stalin turned on the Jews every few years in savage anti-Semitic campaigns, with many Jews killed or sent to labor camps. The so-called "Black Years" were from 1948 to 1953, climaxed by the supposed "Doctors' Plot." The government imprisoned many physicians, mostly Jews, who Stalin falsely accused of plotting to kill top government officials.

After Stalin's death in 1953, government attitudes toward the Jews changed year by year, but turned nasty after June 1967, when Israel triumphed in the Six-Day War. That event prompted the start of a new anti-Jewish campaign by the Soviet government.

But the 1967 war also caused an upsurge in pride among Soviet Jews. For the first time in decades, Jews began to reexamine the Jewish heritage from which they had been alienated by government directive, and began talking about leaving the country for Israel.

Because religious instruction is forbidden and books in Hebrew are extremely difficult to obtain, Soviet Jews interested in their religion have been sustained for years by visiting Jewish American tourists, who bring them contraband reading material and sacred items.

But the pro-Soviet Jewry movement in the United States has been torn apart by divisions for years, the same types of ideological and personal disagreements that have distinguished American Jews' recent discussions of Israel.

A hard-line group, partly composed of some Orthodox Jewish activists and former refuseniks such as Natan Shcharansky, favors strident denunciations of the Soviets. One New York-based group plans acts of civil disobedience here this week and hopes to be arrested. These activists disagree with the much larger Jewish groups, which the hard-liners call "establishment" Jews, who favor a less confrontational approach to dealing with the Soviets.

Today's rally represents the first time that the two factions, and all the major U.S. Jewish organizations, have come together at one event, activists said. One example of the cooperation is that Jozef Mendelevich, who spent 11 years in Soviet labor camps after an unsuccessful 1970 attempt to hijack a Soviet plane and was released to Israel six years ago, will be allowed to speak. Last year, Mendelevich, a hard-liner, angrily grabbed the microphone at a major "establishment" rally for Soviet Jews in New York, and demanded to speak.

Harris, this rally's coordinator, said that organizers have "forged a degree of cooperation and consensus that's truly remarkable."

But some controversies remain.

One concerns where the released refuseniks live. For years Israel, believing it needs the mostly well-trained Soviet Jews being released, has been angered by the United States' acceptance of so many refuseniks after they leave the Soviet Union. About three-quarters of those who have departed recently have come to the United States, for a total of 90,000 Soviet Jews here. There are about 170,000 Soviet Jewish refugees in Israel, most of whom left the Soviet Union in the 1970s.

Most of those released, because they were born after the 1917 revolution and have had very little contact with Jewish culture or religion, prefer the polyglot United States to Israel. Israel refers to those who come to the United States as "dropouts" because so many don't identify with being Jewish and never rediscover it.

"Israel believes that the Soviet Jews coming to America run a greater danger of being assimilated, losing Jewishness," said Jerry Goodman, executive director of the National Conference on Soviet Jewry. "Many get lost, they just sink in."