JERUSALEM — Israeli Defense Minister Ehud Barak abruptly announced Monday that he was leaving the Labor Party — dividing the movement that dominated Israeli politics for decades and setting off a chain reaction that cast new doubts over already troubled peace efforts with the Palestinians.
The split in the iconic party that led Israel to independence did not appear to threaten the majority of Prime Minister Benjamin Netanyahu's coalition. Barak, a former prime minister and military chief, will stay in the ruling coalition with four followers who joined him.
But Labor's eight remaining members, who had been pushing him to leave the government because of the impasse in peace talks, were expected to withdraw. With a smaller but more unified majority and rid of these dissenting voices, the government could find it easier to dig in on hard-line positions.
Labor has been the sole moderate party in Netanyahu's coalition, which is otherwise dominated by religious and nationalist parties that oppose major concessions to the Palestinians.
By mid-afternoon, three Labor Cabinet ministers had announced their resignations.
Barak, one of the most powerful members of the government, said he was tired of the infighting within Labor. He accused his former partners of moving too far to the dovish end of the political spectrum.
"We are embarking on a new path," he said during a news conference at Israel's parliament. "We want to wake up without having to compromise, apologize and explain."
He said the new faction — to be called Independence — would be "centrist, Zionist and democratic." He did not take any questions.
Netanyahu said the Labor shake-up made his government stronger by dashing any hopes the Palestinians might have that his coalition would fall.
"The whole world knows and the Palestinians also know this government will be here in the coming years and this is the government they must negotiate with for peace," he told a meeting of lawmakers from his ruling Likud Party.
Peace talks broke down in late September, just three weeks after they were launched, over Israel's refusal to renew an expiring settlement freeze in the West Bank and east Jerusalem. Since then, Israel has announced plans to build hundreds of homes in the West Bank and east Jerusalem.
The Palestinians refuse to negotiate until Israel freezes construction in those areas, captured by Israel in 1967 and claimed by the Palestinians for a future independent state.
The chief Palestinian negotiator, Saeb Erekat, called Barak's decision a domestic affair, but appeared skeptical of the current government's commitment to peace.
"Unfortunately, the current Israeli government has chosen settlements over peace," he said.
Erekat said the Palestinians this week would ask the U.N. Security Council to condemn settlements — a long-planned move aimed at raising international pressure on Israel.
Opposition leader Tzipi Livni called on Netanyahu to dissolve his government and hold a new election. "The Netanyahu government is falling apart from the inside because of political rot and a lack of vision," she said.
Barak and Netanyahu have had a mutually beneficial relationship. The men have known each other for decades, back to the time that Barak was Netanyahu's commander in an elite commando unit in the army.
As a former prime minister who offered a peace plan to the Palestinians a decade ago that called for uprooting settlements and sharing Jerusalem, Barak has given the governing coalition a well-known and relatively moderate face to deal with the international community.
At times, particularly with the U.S., Barak has served as a de facto foreign minister, replacing Foreign Minister Avigdor Lieberman, an ultranationalist who is often scorned in the West.
Netanyahu, meanwhile, has given Barak extra influence in decision-making out of proportion to the relatively small size of Labor.
But Labor members have grown increasingly unhappy with Barak, accusing him of enabling Netanyahu to stall in peace efforts. Although Barak is an outspoken advocate of peace with the Palestinians, he also takes a tough line on security matters and has moved slower than his critics would like on making concessions.
The Labor rebels also were uncomfortable about sitting in the same government with Lieberman, who has ridiculed the notion of reaching a peace deal and openly questions the loyalty of Israel's Arab minority.
Einat Wilf, a Labor lawmaker who joined Barak, said the defection was in the works for the past 10 days and that Netanyahu was aware of the plan.
"I think the prime minister has not received enough credit for the steps he has taken over the past two years," she told The Associated Press. "We think it is part of our responsibility to strengthen those elements."
Barak's decision took other Labor lawmakers by surprise.
Cabinet Ministers Isaac Herzog, Avishai Braverman and Binyamin Ben-Eliezer quit the government just hours after Barak's announcement.
Barak "spit in the face of the party that elected him," Ben-Eliezer said.
Labor dominated Israeli politics for the country's first three decades, producing a string of prime ministers that included Israel's founding father, David Ben-Gurion, and the slain prime minister, Yitzhak Rabin. Barak himself briefly served as prime minister in 1999-2000.
But in recent years, Labor has been reduced to a midsize party, with just 13 seats in the current parliament. Many party members hold Barak responsible for the party's demise, and accuse him of abandoning its socialist and dovish ideals to remain in power.
Barak's departure from Labor resembled Prime Minister Ariel Sharon's departure from Likud in 2005 to form the centrist Kadima Party in the wake of his pullout from the Gaza Strip. Sharon suffered a stroke shortly after, but his successor, Ehud Olmert, led the party to victory in a 2006 election.
Yohanan Plesner, a Kadima lawmaker, said it was a sad day for Israel. "This is the day the Labor Party was buried for good," he said.