Final opinion polls have put Israeli Prime Minister Benjamin Netanyahu's right-wing Likud party four seats behind its centre-left rival with four days to go before a general election.
Several polls released on Friday - the last day opinion surveys can be released before Tuesday's vote - showed the Zionist Union pulling further ahead of Likud after an intense campaign.
Netanyahu, who gambled by calling the vote nearly two years early after his government coalition fell apart late last year, has warned Israel's security will be at risk if his rivals win.
But the opposition's call for change after nearly six years of rule by the divisive Netanyahu appears to have been heard by many voters.
A poll in the top-selling Yediot Aharonot newspaper showed the Zionist Union winning 26 of the 120 seats in the Israeli parliament, or Knesset, against 22 for Likud.
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Other polls for the Jerusalem Post and Maariv dailies, and for Israeli public radio, also showed a four-seat gap, with the Zionist Union taking 25 seats to 21 for Likud.
All the polls showed the Joint List, a newly formed alliance of Israel's main Arab parties, in third, with 13 seats.
The centrist Yesh Atid of former finance minister Yair Lapid and the far-right Jewish Home were both expected to win at least 11 seats, the polls showed.
The Zionist Union was created in December by fusing Israel's once-dominant Labour party with the centrist HaTnuah led by Tzipi Livni, Israel's former chief peace negotiator with the Palestinians.
Should they form the next government, the parties have agreed on a two-year rotation for the premiership, with Herzog taking the first tenure.
Under Israel's proportional vote system, instead of electing individual members of the Knesset voters choose party lists, with seats distributed according to the percentage of the vote received.
