JERUSALEM -- In a vote that may affect the shape of Israel's next government and the course of Middle East peace talks, Yitzhak Rabin defeated Shimon Peres early today for the leadership of the opposition Labor Party in national elections early this summer.
But in a four-candidate party primary, the first such vote ever conducted in Israel, it was not clear how solidly Mr. Rabin held the 40 percent share he needs to avoid a runoff next Wednesday against Mr. Peres, the incumbent leader and his political rival for nearly two decades.
He was over that mark this morning. But the vote totals were unofficial, awaiting certification later in the day, and Mr. Rabin stopped short of claiming outright victory.
Still, Mr. Rabin, a former prime minister and a former army chief of staff, sounded like the winner for the right to lead the Israeli opposition in the elections for Parliament on June 23 against Prime Minister Yitzhak Shamir's Likud bloc.
He said, "Both the fact that I'm first, and the sectors that supported me, prove how right my claim is that we can beat the Likud if we find the right candidate."
Mr. Peres congratulated Mr. Rabin early today and said he did not plan to appeal the results. He said on Israel radio: "Of course, I would have been happy if the results were otherwise. But I accept this outcome."
It is always possible that a closer look at the totals might bring Mr. Rabin's total below the 40 percent threshold. If there were to be a runoff, some political commentators say, many of the votes that went this time to other candidates could fall Mr. Peres' way, making him a more formidable opponent in a two-way race.
An unofficial, final tally showed Mr. Rabin with 40.6 percent of the Labor Party votes; Mr. Peres with 34.5 percent; Israel Kessar, head of the Histadrut labor federation with 19.1 percent, and Ora Namir, a member of Parliament, with 5.6 percent. It was not clear to whom the small remaining number of votes went.
Mr. Kessar's performance was surprisingly strong. A widely held assumption is that the backbone of his support -- union leaders and Israeli Arabs -- would turn to Mr. Peres in a runoff.
Likud will choose its leader tonight at a meeting of its 3,000-member Central Committee. Political experts say the 76-year-old Mr. Shamir is almost certain to turn back challenges from two ambitious Cabinet members, Foreign Minister David Levy and Housing Minister Ariel Sharon.
A Likud decision this week to require the winner to get only a 40 percent share of the vote to avoid a runoff, instead of 50 percent as before, enhanced the prime minister's chances.