Nearly every morning, a dozen buses depart from Tel Aviv, Jerusalem, Haifa, Ashdod and other major Israeli cities for an extraordinary day trip. The passengers are Russian-speaking Israelis, their destination is the Golan Heights and the purpose of the trip is political: to enlist help in defeating any peace agreement with Syria that includes returning the Golan.

Tens of thousands of immigrants from former Soviet lands--a key swing vote in Israel--have been bused to the Golan Heights in this fashion in the last three months. Once they reach the plateau in the north, they are treated to a tour that is part sightseeing, part seminar. The guides, all of whom speak Russian, hammer home this essential point: Giving up the Golan Heights would mean suicide for Israel, even if the country's military and civilian leadership believes it can be done without compromising security.

The trip is the tip of an iceberg that Golan residents and their allies are directing into the path of Israeli Prime Minister Ehud Barak's peace plans. And, so far, it may be working. More than 60 percent of Israelis--including some key parts of Barak's own constituency--are opposed to trading the Golan for peace with Syria, according to a recent poll.

That could spell big trouble for Barak as he pursues negotiations with Syria that ended their second phase today in Shepherdstown, W.Va., because the prime minister has promised to submit any deal he makes to a referendum of Israeli voters. There may be months more of bargaining before an accord, but already opponents of relinquishing the Golan are raising money, recruiting volunteers and blanketing the country with stickers, banners and bumper stickers to make sure the referendum produces a "no" vote.

"We are stressing this is a crucial moment for the state of Israel," said Avi Zeira, a longtime Golan resident and a top organizer of the Vote No campaign. "The message is that we are not moving from the Golan."

That message was amplified tonight in an enormous demonstration in Tel Aviv organized by the Golan Residents Committee. On a cool, drizzly evening, a crowd estimated at more than 100,000 rallied on Rabin Square to denounce Barak's plan to give back the Golan, which was captured by Israel in the 1967 Middle East war and is now home to 17,000 Israeli Jews.

In the absence of a signed agreement, Barak's allies have not really started to fight back. When they do, they will have all the advantages of office, the support of most of Israel's major media and a quiver of potent arguments.

Barak has framed a deal with Syria as the key to a new era of peaceful relations with the Arab world and a revival of the Israeli economy. He has argued that peace with Syria is the surest way for Israel to end its two-decade occupation of southern Lebanon, where Syria is the main power broker. He has made it known that the three-year army service for Israeli men would be reduced by six months if a deal with Syria is signed and the Israeli army withdraws from Lebanon. And he has warned that to reject a peace agreement would invite regional instability and the possibility of renewed warfare.

Moreover, his background as Israel's most decorated army officer--Mr. Security, in the formulation of his admirers--will be a selling point for any deal. "At the end of the day, the arguments are going to be overwhelming," said Zeev Chafets, a columnist for the Jerusalem Report.

As for the Golan residents, they have little money and even less experience in running a nationwide campaign. And their own political position is complex.

The Golan residents who organized tonight's demonstration are mostly secular Israelis--politically leftist, overwhelmingly of European origin. A majority voted for Barak in last spring's election despite his campaign promise to seek a peace deal with Syria, and most support the principle of trading land for peace with the Palestinians. Tellingly, they held the demonstration on Tel Aviv's Rabin Square, the place where Prime Minister Yitzhak Rabin was assassinated in 1995 and a place of pilgrimage for left-leaning, secular Israelis.

Yet a large majority of the demonstrators were right-wing, nationalist and religious Jews, identifiable by the skullcaps worn by the men and long skirts by the women. They included Jewish settlers in the West Bank, who are among the most bitter opponents of Barak and of handing over West Bank land to the Palestinians.

The division between secular and religious Jews in Israel runs deep, and the Golan residents are keenly aware of it. Mindful that only a minority of Israelis are in the nationalist-religious camp--and in any event are certain to vote against giving up the Golan--the Golan organizers are eager to extend their appeal. Their target voters are secular, moderate and leftist Israelis--including, principally, the Russian-speakers who are uncomfortable with the religious right.

"There are principles that are different," said Marla van Meter, a Golan resident, who acknowledged the uneasy alliance between the two camps. "But the principle that people should not be harmed in the peace process, or communities disrupted, are principles that have been upheld by both sets of activists even though the issues are very different."

In an attempt to present as ecumenical an image as possible, the Golan organizers barred all politicians from the microphone, including Ariel Sharon, a hard-liner who leads the main opposition Likud party. Instead, the speakers were Golan leaders and activists, and their appeal was more emotional than partisan.

"A country without the Golan will be torn and divided," declared Eli Malka, head of the Golan Residents Committee, addressing the crowd and, in absentia, Barak. "The Zionist and pioneering spirit--all this will be lost if we lose the Golan."

In addition to the nationalist and religious camps, some of Barak's own voters may be less than enthusiastic about peace with Syria. Recent polls suggest that more than 20 percent of his own Labor Party's voters, and of the even more leftist Meretz party's, oppose giving up the Golan.

The objections are varied. Many Israelis, conditioned by a generation of venomous rhetorical attacks from Damascus, believe the Syrians are far more interested in recovering territory than making real peace. Their suspicions have been reinforced by the Syrians' reluctance to make conciliatory gestures and by Foreign Minister Farouk Chaara's refusal to shake hands with Barak in public during their meetings in the United States.

Many also believe that the Golan remains critical to Israel's security, or that giving up the Golan smacks of appeasement of the Arabs and would set a dangerous precedent. Many Russian-speaking immigrants, born and reared in an empire that was loath to give up territory, are instinctively suspicious of the notion that the Golan should be ceded. And some religious Israelis see the Golan as having been granted to the Jews by God.

"It's our land; it's as simple as that," said Aaron Knobloch, 51, an American-born computer consultant who lives north of Tel Aviv. "Giving it away is suicidal."

CAPTION: More than 100,000 Israelis rally on Rabin Square in Tel Aviv to protest any land compromise with Syria over Israel-occupied Golan Heights.

CAPTION: Israelis display signs denouncing a plan to give the Golan Heights back to the Syrians.