Israel's defense minister quit the Likud Party on Sunday to join Prime Minister Ariel Sharon's new centrist faction, saying his former party had been hijacked by "right-wing extremists."

The defection of Shaul Mofaz, one of the most prominent Likud leaders, further marginalized the increasingly hard-line party and gave Sharon added momentum as he prepared to campaign for March 28 elections.

Mofaz's decision came after weekend polls showed him badly trailing former Prime Minister Benjamin Netanyahu and Foreign Minister Silvan Shalom in the race to become Likud's candidate for prime minister, but he insisted the party's direction, and not the polls, were what influenced his decision.

"The Likud party ... is growing away from me and, to my sorrow, is moving in the direction of what we call the right-wing extremists of the political map," Mofaz said. "When it became clear that the Likud movement was becoming an extremist party, I decided that this was not my way."

Sharon told aides Sunday that Mofaz called him a day earlier to tell him he intended to leave Likud.

"I suggested he join the Kadima movement and continue serving as defense minister in the next government. He answered affirmatively, and I'm glad," a meeting participant quoted Sharon as saying.

Sharon formed the Kadima Party last month after concluding that the so-called Likud "rebels" who tried to torpedo his Gaza withdrawal plan would work to block any future peace moves with the Palestinians.

The prime minister's exit from Likud left the party, which dominated Israeli politics for much of the last three decades, in tatters.

Many of Likud's parliamentarians and virtually all of its top Cabinet ministers followed Sharon, including — most embarrassingly for Likud — acting party chairman Tzachi Hanegbi, who bolted for Kadima last week, saying Sharon had the best chance to make peace with the Palestinians.

Sharon tried to persuade Mofaz to join him when he formed Kadima, but the defense minister chose to stay and run for the Likud leadership.

Recent polls show Kadima capturing 39 seats in the 120-member Knesset, making it by far the largest party and propelling Sharon back into the prime minister's office as head of coalition seeking to restart peace efforts with the Palestinians.

Likud, which won 40 seats in the last election, would capture between nine and 13 seats in the March 28 vote, according to recent polls.

Mofaz's defection was likely to attract even more Likud voters. The Iranian-born Mofaz, 57, has strong security credentials — assuming the position of defense minister shortly after retiring as the military chief of staff.

His departure further strengthened the hard-liners in Likud. Netanyahu, who quit Sharon's government in opposition to the Gaza pullout, is the current front-runner to win the Dec. 19 Likud primary.

Likud official Uzi Cohen said the Likud "rebels," who rejected Sharon initiatives after the Gaza pullout, damaged the party.

"The movement, the party, suffered terribly from the rebels who were not prepared when the moment came to climb down," Cohen told Israel Radio.

Sharon, who also recruited veteran Labor Party leader Shimon Peres to Kadima, said that if re-elected, he hopes to restart peace talks based on the "road map," an internationally backed peace plan that aims to create a Palestinian state.

New Labor Party leader Amir Peretz, whose poll standing fell after a deadly Palestinian suicide bombing last week, called the phased plan a "waste of time" and said he favored moving straight to negotiations to resolve the conflict once and for all.

"I will work to reach a final status arrangement between Israel and the Palestinians as soon as possible," Peretz told the Yediot Ahronot daily newspaper. "The final status arrangement should be accelerated, instead of the 'road map."'