Long before the candidate arrives, the young Oriental Jews who gather almost nightly for festive campaign rallies start the haunting, singsong chant that has come to symbolize the remarkable political renaissance of Menachem Begin while serving as the anthem of a quiet revolution within Israel's largest ethnic bloc.

Although private political polls and newpaper samplings show Labor Party candidate Shimon Peres pulling from behind in the last few days of the campaign to within reach of Begin for Tuesday's election, the prime minister is clearly the favorite of the noisy summer crowd.

"Be-gin, Be-gin, Be-gin," chant the swarthy immigrants or children of immigrants from Morocco, Yemen, Iraq, Syria, Iran and across North Africa, the Middle East and West Asia, where Jews have abandoned their ancestral homes to emigrate to Israel.

Some strip off their perspiration-soaked shirts in the sultry air as the crowd surges forward against police barriers in anticipation of the arrival of the object of their adminiration. Then, as a pale man in a dark suit and thick glasses from Brest Litovsk, Poland, mounts the speaker's platform, mounts the speaker's platform, 30,000 people chant:

"Be-gin, Be-gin, Melech Yisrael!" (Begin, Begin, King of Israel!").

It is a chant drawn from a joyous folk tribute to David, king of biblical Israel, that Israeli children learn by the third grade and that is normally reserves for national heroes.

If, by outward appearances, Menachem Begin of the Old World is an incongruous subject for idol worship by the Sephardic Jews who make up 53 percent of Israel's population, the contradiction has long since been lost in one of the most emotionally charged political campaigns in Israel's 33-year history.

If Begin and his rightist Likud ticket win when approximately 80 percent of Israel's 2.4 million voters to go to the polls Tuesday, it will be the upheaval of Israel's new social structure that will be responsible for his reelection.

It is an upheaval that some political and social scientists maintain will lead within a decade to a Sephardic prime minister and a fundamental shift of the political structure and ethnic balance of power of a country founded by and dominated since 1948 by Ashkenazic Jews of European origin.

But for now, it is Begin -- eight times a loser in his quest for power until his rightist Likud Party finally won in 1977 -- who stands to gain as a result of the polarization of the Sephardic and Ashkenazic electorate.

This year's campaign for election of the 120 members of Israel's parliament, who in turn will elect a prime minister to a four-year term, has been dominated by the ethnic question in one form or another. The ethnic electorate has attached itself to Begin almost as a personality cult, identifying with the Likud's strong populist undercurrents and rejecting the opposition Labor Party as an "elitist" body that has systmatically excluded Sephardim since the days of the yishuv that preceded statehood in 1948.

Peres, who has been preparing for this electoral battle since his days of apprenticeship under David Ben-Gurion, had been almost immobilized -- snakebitten, some of his aides say -- by the ethnic factor until the closing days if the race.

In his frustration, he lashed out at Begin for "rabble-rousing" and "Khomeinsim." This, in turn, focused even more attention on ethnic divisions in the country, where Sephardic Jews are openly called "blacks" and Ashkenazic Jews are referred to as "whites." It has obscured substantial issues of the campaign in a murky cloud of verbal violence and, to an unprecedented extent, ugly physical clashes between supporters of the two parties.

Israeli police have brought charges against more than 200 persons in recent weeks, most of them young Likud supporters, because of election violence ranging from gang assults at rallies to burning and looting local opposition party headquarters and vandalism of automobiles bearing party bumper stickers.

The violence has become almost an obsessive issue in the campaign, with the Labor Party harking back to prestate days of terrorism by Begin's underground Irgun movement and Begin-led riots in 1952 during a bitter national debate over the acceptance of German reparations for Nazi atrocities against Jews in World War II.

"Yes, Menachem Begin, you are responsible!" shouts one Labor Party campaign advertisement. "One and all recognize the pictures of thugs before us these days . . . Fundamentally, you remain what you have always been."

Outraged, Begin and his Likud supporters have dredged up bitter memories of the forebears of the Labor Party turning over members of the Irgun and Stern Gang to British authorities for hanging. The tone of the campaign prompted Moshe Etzioni, chairman of the Elections Commission, to decry the "vulgarity" of both parties and say, "There are intelligent people running these campaigns. Why do they resort to such things?"

Obscured in the emotions and bitter rhetoric have been issues that three months ago both parties thought would dominate the debate:

The steadily deteriorating economy, with inflation at 130 percent annually and with government spending exceeding the gross national product.

The steadily declining immigration of Jews and an alarming rate of emigration from Israel.

The future of the occupied West Bank and Gaza Strip.

Israel's place in the strategic alliance sought by the Reagan administration in hopes of stemming Soviet influence in the Middle East.

Also overshadowing substantial domestic issues has been Begin's success in exploiting the crisis over deployment of Syrian missiles in Lebanon in April and the bombing of Iraq's nuclear reactor June 7. Besides drowning out the issues on which Begin would have been most vulnerable, the crisis atmosphere placed Peres in the untenable position of having to support the Likud's national security position or appearing unpatriotic.

The more strident Begin's anti-Syrian and anti-Iraq rhetoric became, the more support he seemed to gain from Israeli voters who have traditionally loathed and feared those two Arab states.

Begin has successfully capitalized on both issues, portraying his hard line against the missiles as a guarantee against terrorist attacks by Palestinian guerrillas across Israel's northern border and characterizing the bombing of the reactor as an act of "national redemption" that prevented a future nuclear genocide.

His stream of campaign statements about the attack on Iraq so irritated Peres that the Labor Party leader branded it "nuclear chatter." But other candidates recongnized the appeal of such talk and quickly jumped on the bandwagon. They included former foreign minister Moshe Dayan, who declared that Israel has the capacity to produce nuclear weapons and should be ready to do so if the Arabs produce them first.

But, three days before the election, it has become clearer than ever before that the ethnic electorate has been primariy responsible for Begin's extraordinary comeback from virtual political ruin six months ago.

In January when Begin's fractious Cabinet averted certain collapse by calling for an early election, public opinion polls forecast a 58- to 20-seat victory for the Labor Party. Two weeks ago polls indicated a 48- to 39-seat edge for Likud, althrough more recent sampling shows the two parties running about even.

Because the pivotal religious parties expected to win 14 or 15 seats are more likely to go to the Likud than the Labor Party in formation of a government, the polls appear to give Begin a distinct edge in forming a coalition. Sixty-one seats are needed to form a coalition government.

Under Isreali law, the party winning the most seats in parliament is given the opportunity to form a coalition government.

But a party that runs second can, in effect, form an amalgam with prospective coalition partners and gain the first opportunity to form a government. Therefore, Likud could end up with the same number of seats -- or even fewer -- than Labor and still form the next government, because of its advantage of close alliance with the religious parties.

The resurgence of Begin's popularity in Sephardic society has been attributed variously to his hawkish position against surrounding Arab states and to generous tax-cutting and price-slashing by his controversial finance minister, Yoram Arridor.

However, the explanation probably lies deeper than that and is to be found in the long-overlooked alienation of Oriental Jews in Israel society. For 30 years, Begin led the opposition to a succession of Labor Party governments from the back benches of parliament. By default, if nothing else, he became the recognized spokesman for an ethnic group that felt cut off from the mainstream of Israeli politics.

The fact that his prestatehood Irgun movement was open to Oriental Jews while the Ashkenazic Hagana army was not also helped Begin attract the Sephardic Jews. Moreover, Begin, at 68, has adopted an almost patriarchal aura that has appealed to many Oriental Jews from Arab countries where patriarchic structure was strong.

He is also a superb orator in Hebrew, even his critics admiringly admit, and he has mastered the formula for exciting and charming crowds of listeners. When his audience chants "Begin, King of Israel," Begin tilts his head in mock embarrassment and protests, "I am not a king, but just a simple ordinary man." Then he adds, "I am a republican, in fact," and his audience erupts into even more frenzy.

Begin is also, in the words of one aide, a "visceral Jew," a man who is more Jewish than Israeli, while Peres tends to appear more Israeli than Jewish.

"I'm an old Jew," Begin likes to begin his monologues, and to a segment of society that frequently feels cut off from an increasingly secular Israel, that has enormous appeal.

In the face of Begin's populist-oriented campaign steamroller, engineered almost single-handedly with his contentious and unpopular Cabinet ministers purposefully relegated to the background, Peres and the Labor Party have been scrambling in near panic.

Peres belatedly went on the offensive last week -- after a disorganized and lackluster campaign -- by focusing on campaign violence and attempting to portray Begin as unpredictable and dangerous as a leader.

And in a move made out of apparent desperation, he attempted to create an atmosphere of unity in the divided Labor Party by nominating as his prospective defense minister his archrival, former prime minister Yitzhak Rabin.

Labor Party sources said today that although Peres has managed to close the gap, the impact of the Rabin appointment and Peres' solid showing in a face-to-face televised debate with Begin Thursday probably would not be felt fully by election day.

"We're hoping we've done enough, at least, to turn a significant number of voters away from the smaller parties ot Peres," a senior campaign adviser said.

But whether these ractical counter-measures will be enough to turn back the quiet revolution that is taking place in Israel's social structure is far from certain. If they are not, then the long-disaffected Oriental Jews will have demonstrated their influence in Israel's electoral politics long before they install in the prime minister's office an ethnic candidate of their own.