Israel's largest Arab party grouping said Thursday it would recommend opposition leader Gadi Eisenkot to form the next government, strengthening his bid after Arab-majority lists captured a record 19 seats in last week's election and Prime Minister Benjamin Netanyahu lost the backing of a longtime religious ally.

President Isaac Herzog held a second day of consultations with political parties following the October 27 vote, in which neither Netanyahu, a polarising right-winger who has led Israel through three years of war, nor Eisenkot, a former military chief promising to restore national unity, secured enough support for a majority.

Herzog alone decides whom to task with forming a government, but the mandate traditionally goes to the candidate recommended by the most parties, which in this case would be Eisenkot.

Both Arab lists announced their support for Eisenkot on Thursday. The Joint List, which won 11 seats, said in a statement that "it will inform the President of the State, Isaac Herzog, this evening of its decision to recommend that Gadi Eisenkot be tasked with forming the government". Raam, which took eight seats, also endorsed him.

Meanwhile, United Torah Judaism, which had backed Netanyahu after the previous five elections, declined to recommend him again in its meeting with Herzog, though it also stopped short of siding with Eisenkot. The party informed the president "that it has decided not to recommend any member of Knesset to form a government", the president's office said, referring to the 120-member parliament in which the party holds seven seats.

United Torah Judaism, alongside Shas, another ultra-Orthodox party, has pushed to preserve the exemption from military service for religious students. Netanyahu kept the exemption in place but stopped short of enshrining it in law, in the face of deep resentment from many other Israelis as reservists serve multiple tours because of the wars in Gaza, Lebanon and Iran. "In whatever government is next formed, our immediate item is sorting out the status of Torah students," United Torah Judaism lawmaker Isaac Pindrus said.

Eisenkot, who has tried to appeal to secular Israelis from left to right, has been adamant about ending the exemptions. Some of his opposition allies have criticised the ultra-Orthodox, who make up about 14 percent of the population but have far higher birthrates than secular Israelis, as a drain on the state. Observers say United Torah Judaism's tactic is likely aimed mostly at punishing Netanyahu and showing that its votes cannot be taken for granted, while the party would still serve in a government if he were to form one.

Once Herzog gives his mandate to a lawmaker, that person will have 28 days to form a government, with a potential 14-day extension. If the lawmaker fails, Herzog will then task someone else. Netanyahu's bloc, including United Torah Judaism, holds 53 seats in the new parliament, compared with 48 for Eisenkot's bloc.

Arab-majority parties scored historic gains on the back of anger over Netanyahu's hard-right government, whose ministers have vowed to treat Arab Israelis much like Palestinians in war-ravaged Gaza and the occupied West Bank. Eisenkot could form a government with the Arab parties' numbers, but he would risk losing support from some in the opposition, notably Avigdor Liberman, a former Netanyahu aide turned outspoken critic who nonetheless shares the outgoing government's hawkish views on the Palestinians. Netanyahu has relentlessly attacked the opposition over even the prospect of an alliance with Arab lawmakers, and in a video filmed in the prime minister's office that circulated Wednesday, he alleged there were "serious suspicions" that foreign powers had put money into the election and questioned the loyalty of Arab citizens.