CAIRO, Egypt – Prime Minister Sharon’s decision to leave the party he helped create will leave Likud free to press for the retention of territory won in the 1967 Six-Day War while paving the way for a likely Labor government when Israelis next vote in parliamentary elections this spring.

The realignment in Jerusalem following the dramatic announcement from Mr. Sharon on Sunday night has already prompted Mr. Sharon to ask for the dissolution of the Knesset and new elections for the legislative body, expected to be held at the end of February or in early March.

The split in Likud has opened the door for a former prime minister, Benjamin Netanyahu, to lead a weakened Likud in opposition to any further unilateral repositioning of Israeli soldiers. Mr. Sharon has said that his new party, tentatively to be called “National Responsibility,” will adhere to an international plan known as the “road map” aimed at negotiating a Palestinian Arab state carved from the West Bank and Gaza. Meanwhile, Labor Party leaders are expecting big gains this spring.

At a press conference last night, Mr. Sharon said his new party would seek implementation of a final settlement with the Palestinian Arabs. “We have two tasks facing us. One is to lay the foundations for a peace settlement,” he said. “Disengagement provided us with a historic opportunity, and I do not intend to allow anyone to miss this opportunity.”

In explaining why he left the party he helped build nearly three decades ago, Mr. Sharon said, “The Likud in its present configuration cannot lead the nation to its goals. I founded the Likud to give hope to Israel. Unfortunately, this is no longer there. If I had stayed, I could have won the primaries and led the Likud to victory in the election. Staying in the Likud would have meant wasting time with politics instead of working for the good of the nation. I prefer the good of the nation over comfort and ease.”

The defection of the prime minister from his party paves the way for Mr. Netanyahu, who for the past year has been leading a revolt within Likud opposing the withdrawal of Israeli settlers and soldiers from Gaza. Last week Mr. Netanyahu blasted the Sharon government for approving, under American pressure, a new agreement to open the border between Gaza and Egypt.

In an interview with United Press International published on November 16, Mr. Netanyahu said he would only trade “peace for peace” with the Palestinian Arabs, and pointedly avowed to oppose any negotiations as long as Israeli citizens were under threat of terror attacks. Mr. Netanyahu agreed in 1998 for the CIA to train Yasser Arafat’s security organizations, a decision since criticized by his party because it provided guns and know-how to agents that ended up cooperating with terrorists, not arresting them, in 2000 at the start of the intifada.

Already Mr. Netanyahu has managed to lure Defense Minister Shaul Mofaz from Mr. Sharon’s new party. “In recent weeks I have said more than once that I’ll stay in the Likud. I decided to stay in the Likud, and I plan on running in its primaries,” he said at a press conference at the Ministry of Defense. Hinting that he may run for leadership of the Likud himself, Mr. Mofaz said, “I think that these days the Likud needs a leader who can combine security experience, statesmanship, and social issues.”

Another possible challenger for the Likud leadership is Knesset member Uzi Landau, who is often referred to as the leader of Likud “loyalists” in Israel’s parliament. Last week, as rumors of Mr. Sharon’s defection began percolating in Jerusalem, he told Israeli journalists that he would likely become his party’s new leader.

“Likud will become a further right party, rather than right-center. If Bibi leads, it will exist for the first time as a neoconservative party that is strong on national security and supporting free markets,” a Middle East expert at the Hudson Institute, Meyrav Wurmser, said yesterday. “Likud will also likely shrink. It will be a major political expression for greater Israel even though they are likely to shrink.”

Mr. Sharon is looking to the left for recruits to his new party. Before announcing his decision to leave Likud, Mr. Sharon at the Sunday cabinet meeting directed comments former Labor Party leader, Shimon Peres, urging him to stay with him to complete what they started. Yesterday Israel’s Channel 2 television reported that Mr. Sharon will ask Ehud Barak to be his defense minister. Mr. Sharon trounced the former prime minister in 2001 after criticizing the Labor premier of negotiating with Yasser Arafat as he sent suicide bombers to Israeli schools and shopping malls. Ironically, it’s Mr. Sharon’s own party that is likely to employ a similar line against Mr. Sharon if any attacks occur between now and the elections tentatively scheduled for March.

In Washington the State Department offered no comment directly on what spokesman Sean McCormack said was a matter of Israel’s domestic politics. Mr. McCormack did say he expected work to continue on implementing the Gaza border agreement Secretary of State Rice helped forge last week in Israel. “I would expect that while, of course, Israel is answering domestic political questions that the work on implementing this agreement will continue to move forward,” he said.

The Palestinian Authority’s chief negotiator, Saeb Erakhat, said Sunday that Mr. Sharon’s decision to leave Likud was a “political volcano.” “It is happening because of us, [the] Palestinian-Israeli conflict, and I have not seen anything more significant in Israel since 1967, when the occupation came to my home town [of] Jericho,” he said.

Meanwhile, a Labor Party member, Yitzhag Herzog, predicted that his party, currently sharing power with Likud, would emerge as an electoral victor in the next elections. “The new development of the split in Likud will help us become perhaps the biggest party in the next election,” he said. “This development opens the way, opens the door, for a fascinating coalition of moderate forces after the election.”

Yesterday, Israel’s president Moshe Katzav said he would consider Mr. Sharon’s request to dissolve the Knesset. It is reported that Mr. Sharon will bring 14 out of the Likud Party’s 40 members in Knesset to his new party.