Jerusalem ? A former prime minister and a political newcomer who both pledge to bring down Prime Minister Ehud Olmert’s government will face each other in a runoff after an inconclusive vote for leadership of Israel’s Labor Party, final results showed today.

Former Prime Minister Ehud Barak edged out Ami Ayalon 36 percent to 31 percent in Monday’s voting. While the victory marked an important milestone in Barak’s political comeback, he fell short of the 40 percent threshold needed for an outright victory, setting up a June 12 runoff against Ayalon.

The current Labor leader, Defense Minister Amir Peretz, finished third with 22 percent.

Labor has served as the junior partner in Olmert’s year-old government.

But a victory by either Barak or Ayalon is expected to shake up that alliance. Both have called for Olmert’s resignation in the wake of a highly critical government report on his performance during last summer’s war in Lebanon.

Ayalon, a former navy chief and ex-head of the Shin Bet internal security agency, entered parliament only last year. He won support as a newcomer to the political scene, while also holding the security credentials demanded by Israeli voters.

Ayalon, 61, has pledged to lead the centrist Labor out of its year-old partnership with Olmert if the prime minister’s Kadima Party does not choose a new leader.

“I think many people understand that we are, in fact, not just voting on the future of the Labor Party but to a very large extent on the future leadership of the state of Israel,” he said at the northern Israel polling station where he cast his ballot.

Barak, meanwhile, tried to persuade voters that his experience made him the best man for the job. A former military chief and the country’s most decorated soldier, the 65-year-old served as prime minister from 1999 to 2001.

Barak has said he would serve temporarily in an Olmert government, while also pushing for early elections. Olmert was elected last year to what is supposed to be a four-year term.

Opinion polls forecast the hard-line Likud Party, led by former Prime Minister Benjamin Netanyahu, would win a new election.