Prime Minister Benjamin Netanyahu was in a battle for political survival after exit polls following Tuesday’s election showed the race too close to call and the Israeli leader’s decade-long grip on power slipping.

Netanyahu’s main election challenger, centrist Benny Gantz, said on Wednesday it appeared from the exit polls that Israel’s longest-serving leader was defeated but that only official results would tell.

In his own speech to right-wing Likud party faithful, Netanyahu, sipping water frequently and speaking in a hoarse voice, made no claim of victory or concession of defeat, saying he was awaiting a vote tally.

Netanyahu’s appearance in the dead of night at Likud election headquarters was a far cry from his triumphant declaration five months ago that he had won a close election. His failure to form a government after the April ballot led to the new election on Tuesday.

Gantz, a former armed forces chief, beamed with confidence as he told a rally of his Blue and White Party that it appeared “we fulfilled our mission”, and he pledged to work towards formation of a unity government.

Netanyahu, he said, apparently “did not succeed in his mission” to win a fifth term.

“We will await the actual results,” Gantz, 60, said.

The final election results can take more than a week, but partial results are published by the Knesset as the vote-counting proceeds, so a clearer picture will likely emerge within a day before the final tally.

By 6am about a quarter of the votes had been counted.

Revised surveys by Israeli TV stations, several hours after polls closed, gave Likud 30 to 33 of parliament’s 120 seats, a slight drop from earlier forecasts, versus 32 to 34 for Blue and White. Neither had enough support, at first glance, for a governing coalition of 61 legislators, and Netanyahu’s ally-turned-rival, former defence minister Avigdor Lieberman, emerged as a likely kingmaker as head of the far-Right Yisrael Beitenu party.

The updated polls showed that without Yisrael Beitenu’s projected eight to nine seats, stalemate could ensue: Likud would have the support of only up to 55 legislators, down from 57 in the earlier exit polls, for a right-wing coalition. Blue and White could enlist the backing of no more than 59 for a centre-left government.

Netanyahu, who highlighted his close relationship with US President Donald Trump during the campaign, said in his 3am speech at Likud election headquarters in Tel Aviv that he intended to establish a “strong Zionist government” that would reflect the views of “many of the nation's people”.

His description of a future administration appeared to open the way for Jewish parties not part of his current government to join.

It also seemed to be a swipe at Gantz, and the possibility that Netanyahu’s rival might try for a governing coalition with the tacit support of an Arab party, which many right-wingers see as disloyal to Israel.

The Joint Arab List made a strong showing in Tuesday’s election and was projected to capture 13 to 15 seats in the legislature.

Coalition-building could be complicated: Lieberman has said he would not join an alliance that included ultra-Orthodox parties — Netanyahu’s traditional allies.

Lieberman ran on a platform largely focused on weakening the influence that religious parties have on everyday life in Israel.

Gantz has ruled out participating in an administration with Netanyahu, if the Israeli leader is indicted on looming corruption charges.

Dubbed “King Bibi” by his supporters, Netanyahu, 69, had already been stung by the April poll.