A former defence minister, a one-time TV journalist, an ex-mayor and a scion of one of Israel's top political families faced off on Monday in a fight for the leadership of the Labour party.
The once-mighty party, now reduced to eight seats in the 120-member parliament, has been without a chairman since Defence Minister Ehud Barak jumped ship in January to form the centrist "Independence" movement.
Polls across the country were open for 12 hours and closed at 10:00 pm local time (1900 GMT), with results expected at around midnight (2100 GMT).
Public radio put the turnout at 62 percent.
The 66,310 Labour members eligible to vote in the primary were choosing between Shelly Yacimovich, Amir Peretz, Isaac Herzog and Amram Mitzna. Peretz, 59, and Yacimovich, 51, are considered the front-runners.
Speaking to reporters as she prepared to vote in Tel Aviv, Yacimovich said it was a two-horse race and asked Herzog and Mitzna voters not to split the ballot.
"The choice at the end is between two candidates, either me or Amir Peretz," she said. "That is the message, don't waste votes."
If none of the candidates wins 40 percent of the poll, a second round will be held on September 21.
Whoever wins is unlikely to be fighting a general election anytime soon. The next parliamentary poll is scheduled for 2013 and Prime Minister Benjamin Netanyahu's right-wing coalition is considered stable, with command of 66 parliamentary seats.
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"Labour is now a small opposition party with dreams of becoming medium-sized," the left-leaning Haaretz daily wrote on Monday, adding that the winner of the primaries would be the seventh Labour leader in a decade.
"This is a party that devours its leaders and spits them out," it wrote.
In its 1969 heyday, Labour held 56 parliamentary seats.
Formerly a leading journalist and television presenter who was elected to parliament in 2006 under Peretz's patronage, Yacimovich has been enjoying the support of the Israeli media, praised for her clear social agenda and hailed as the faltering Labour party's last hope.
Peretz, who once headed Israel's Histadrut trade union federation, was defence minister during the 2006 Lebanon War which claimed the lives of 1,200 people in Lebanon, mainly civilians, and 160 Israelis, mostly soldiers, and was widely considered a failure by Israelis.
He gave up the portfolio the following year, after losing to Barak in a party leadership battle.
Herzog, who has held several cabinet posts, is the son of Israel's sixth president Haim Herzog, and his aunt was married to noted Israeli diplomat and statesman Abba Eban.
While many deem him a talented administrator, many also consider that he lacks the charisma needed to lead the party's rehabilitation.
Mitzna, a retired general, has served as mayor both of the northern port city of Haifa and the gritty southern town of Yeroham.
He won the November 2002 Labour leadership contest but quit the job six months later after taking his party to what was then its worst defeat since the country was founded in 1948, ending up with just 19 parliamentary seats.