Prime Minister Benjamin Netanyahu looked set for victory Wednesday as the preliminary vote count in Israel's elections put his Likud party well ahead of its nearest rivals in a result likely to further strain relations with the Palestinians.
With around 70% of votes counted, Likud was leading with 23.73%, the Central Elections Committee said, with the centre-left Zionist Union trailing on 19.06%.
Public radio said the data represented 30 seats in the 120-member parliament for Likud and 24 for the Zionist Union.
Netanyahu had earlier claimed victory in elections Tuesday and the initial results seemed to ensure him a third straight term, likely to further strain relations with the Palestinians.
"Against all odds we achieved a great victory for the Likud. We achieved a great victory for the national camp under the leadership of the Likud. We achieved a great victory for our people of Israel!" Netanyahu told cheering supporters at campaign headquarters in Tel Aviv.
"Now we have to build a strong and stable government," he added.
Exit polls published on two TV stations as polling stations closed had given Likud and Zionist Union 27 seats each in the 120-member parliament. A third poll gave Likud a one-seat lead.
Netanyahu had put security at the forefront of his campaign, arguing he is the only one capable of protecting Israel from an Iranian nuclear threat and vowing never to allow the Palestinians to establish a capital in east Jerusalem.
The Palestinians vowed to step up their diplomatic campaign for statehood.
"It is clear that Prime Minister Benjamin Netanyahu will form the next government, so we say clearly that we will go to the International Criminal Court in the Hague and we will speed up, pursue and intensify" all diplomatic efforts, chief negotiator Saeb Erakat told AFP.
"Everything is open," he told activists in Tel Aviv. "I intend to make every effort to build a real social government in Israel."
In a late appeal to the far-right ahead of the polls, Netanyahu ruled out the establishment of a Palestinian state if reelected, effectively reneging on his 2009 endorsement of a two-state solution.
Herzog has repeatedly called for the creation of a Palestinian state alongside Israel.
Netanyahu made a last-minute call on his supporters to go to the polls to counter a high turnout among Arab Israelis.
"The rule of the rightwing is in danger. Arab voters are going to the polls in droves!" he said in a video on Facebook. "Go to the polling stations! Vote Likud!"
According to exit polls the main Arab parties took third place with 13 seats after joining forces to challenge the premier.
Some 5.8 million people were eligible to vote, with 25 parties vying for the Knesset.
Turnout was 71.8%, up from 67.8% in 2013.