Former Israeli Finance Minister Benjamin Netanyahu announced Tuesday that he would seek to oust Prime Minister Ariel Sharon from the premiership and as Likud leader, accusing the prime minister of caving in to terrorism by relinquishing the Gaza Strip to the Palestinians without getting anything in return.
The battle for control of the Likud - which means "unity" in Hebrew - ratchets up momentum among Israeli lawmakers to dissolve parliament and hold early elections. Opening a campaign now is likely to delay any new push for peace negotiations with the Palestinians.
The challenge from Mr. Netanyahu, who resigned from Mr. Sharon's cabinet on the eve of the withdrawal from Gaza and parts of the northern West Bank, highlights how Likud's ideological crisis over unilateral pullback threatens to tear apart the party that has run Israel's government for 20 of the past 28 years.
"The person who accepted our principles to lead the movement in the spirit of the Likud has turned his back on us," said Netanyahu, who called a press conference in Tel Aviv to make the anticipated announcement. "Ariel Sharon abandoned the principles of the Likud, and chose a different path - the path of the left."
It's the first time any sitting Israeli prime minister has faced being overthrown by a politician of the same political stripe, and analysts say it reflects how the evacuation of 25 Jewish settlements this month in the Gaza Strip and the West Bank could remake Israel's political map.
A series of polls published in Israeli newspapers showing Sharon trailing Netanyahu among Likud members has spurred speculation the prime minister will break ranks with the party that he helped establish in the mid 1970s.
Some have suggested the prime minister could join with Labor leader Shimon Peres and Yosef Lapid, the leader of the centrist Shinui party, and form a political alignment straddling the center of Israeli politics.
Others say that Sharon will be reluctant to strike out on his own, taking caution from the failed attempts by prominent Israeli politicians at setting sustainable centrist political parties.
"There needs to be a realignment, because the dominant party for the last 20 years is going through a severe identity crisis. No one who votes for Likud today knows what they're voting for," says Sam Lehman Wilzig, a professor of political science at the Bar Ilan University.
"It's as if the Republican [Party in the US] would be split between the moral majority and the more moderate pro-business wing. Here we're talking about the core salient ideological issue of Israeli politics ripping the Likud right down the middle."
Netanyahu will appeal to party hardliners who have clung to the dogma of Israel's Revisionist Zionists, a forerunner to the Likud that aspired to establish Jewish sovereignty over all the biblical land of Israel and rejected partition with the Palestinians.
Netanyahu, a former prime minister who served under Sharon first as foreign minister and then as finance minister, accused Sharon of continuing the concessions of the dovish Labor governments during the era of the Oslo peace process. He vowed that any future territorial concessions to Israel's Arab neighbors would be put to a national referendum, hinting at often voiced criticism that Sharon lacked a political mandate for the Gaza withdrawal.
To maintain his support, Sharon will probably rely on Likud pragmatists who recognize that Israel cannot rule over a rapidly growing Palestinian population in the West Bank. They say it should instead shore up control over large blocks of Jewish settlements while demanding the Palestinians rein in militants before restarting peace negotiations.
Israeli elections are scheduled to be held in November 2006, but many have predicted that Sharon's current coalition would become unglued shortly after completion of the unilateral disengagement from Gaza and the northern West Bank, forcing an early vote.
A Likud judicial body approved a move to convene the party's central committee before the end of September, a meeting which is likely to set a date for a leadership primary vote.
Meanwhile, the Labor party, the Likud's traditional rival, has yet to select a leader who would become its candidate for prime minister. Although he has lost four election campaigns, Mr. Peres is a front runner in the party for the nomination. Lawmakers from Labor said that the uncertainty means that a breakthrough in negotiations with the Palestinians is unlikely.
"For a major move to take place, you need a sense of political stability,'' said Yuli Tamir, a Labor parliament member. "The time of the election is quite unclear, and it's unclear even who will participate. It's safe to say that nothing will happen before the elections."