Israeli Prime Minister Benjamin Netanyahu might not be able to secure enough seats to form a new government, election exit polls suggest.
Forecasts put Mr Netanyahu's Likud party and its allies at least seven seats short of the 61 threshold in the 120-seat parliament.
Parties opposed to the prime minister staying in office look set to win 60.
Mr Netanyahu - Israel's longest-serving leader - has vowed to form a right-wing government led by his Likud party.
A smaller right-wing party, Yamina, led by former Netanyahu loyalist Naftali Bennett, is forecast to win seven seats, but has not explicitly declared which side it will support.
"I will do only what is good for the State of Israel," Mr Bennett said in a statement after the exit polls were released.
He added that he had told Mr Netanyahu that Yamina would await the final results before deciding on its next steps.
Israel's Central Elections Committee does not expect all of the votes to be counted before Wednesday afternoon due to coronavirus-related restrictions.
Election hopes and fears play out in crater town
Mr Netanyahu thanked his supporters in a tweet late on Tuesday. "You gave a huge win to the right and Likud under my leadership. Likud is the biggest party by far."
"It's clear most Israelis are right-wing, and want a strong, stable right-wing government," he added.
Meanwhile the main opposition leader Yair Lapid, whose centrist Yesh Atid party is projected to win between 16 and 18 seats in the Knesset, said he was "proud" of his party's "enormous" achievement.
"I have already begun this evening to hold talks with some of the leaders of the bloc for change and will continue in the next few days," he said, adding that he would "do everything possible to establish a sane government in the State of Israel".
Just over 67.2% of those eligible cast their ballots in the election, which was widely seen as a referendum on Mr Netanyahu's leadership.
The 71-year-old prime minister has been in power continuously since 2009, having served an earlier three-year term in the late 1990s.
His campaign focused on Israel's world-leading Covid-19 vaccination programme and his diplomatic success in normalising ties with some Arab countries.
But his opponents from across the political spectrum argued that he should not remain in office while standing trial on corruption charges. He denies any wrongdoing.
After the previous three elections neither Mr Netanyahu nor his rivals were able to form a stable governing coalition.
The current national unity government, which was the result of a power-sharing deal with Defence Minister Benny Gantz, collapsed in December after just seven months.
Mr Gantz, whose Blue and White party is projected by the exit polls to win seven seats, said on Tuesday that he would "do everything I can to unite the pro-change bloc" - a reference to those wanting a new prime minister.
If negotiations to form a government fail again, it could force a fifth election.
The town of Mitzpe Ramon is recovering from its isolation in the desert. Often the inhabitants had only themselves and their crater for company.
The population of 5,211 lives on a cliff edge above a naturally formed chasm in the Negev desert - a site of stunning beauty that entices tourists.
But the visitors vanished amid the Covid closures. The lockdown laid waste to work for the tour guides. In Israel, joblessness has soared.
The country suffered badly as the virus surged last year and there were claims of government blunders.
Then came a dramatically swift vaccine rollout. A battered economy is starting to reopen. Many of these things were weighing on Israel's already crisis-hit coalition, when gridlock triggered yet another election.
But in Mitzpe - the town whose name means "lookout" - no-one seems to be watching much.
The streets don't echo with the sound of political rallying. Election posters are as unlikely to be seen as foreign tourists.
'No to Bibi'
Instead there's a desert wind and weariness. The same bitter divisions over Prime Minister Benjamin Netanyahu's leadership - splits formed years ago - look set to play the major role in Tuesday's poll, the fourth since 2019.
"It's no, no, no to Bibi and his friends," says Boaz Katz, who runs Desert Prime tours. He has seen business drop by two-thirds since the start of the pandemic.
Netanyahu trial: What are the allegations?
Netanyahu: Commando turned PM
He steers his 4x4 over rocks into the crater's core, hinting at worries shared by many Israelis.
"I think about the future a lot and it spooks me to see Benjamin Netanyahu and his natural companions - I want to live in a free, democratic country," says Mr Katz, who used to vote for Mr Netanyahu's Likud party.
The prime minister has been met with protests over his desire to rewire parts of the justice system while on trial for corruption. Others oppose his long-standing pact with ultra-religious parties.
The tour guide scratches a heart shape in the sand and explains the landscape.
The crater was not formed by an asteroid smashing into Earth. Instead, it was scoured out over millennia through water erosion, as torrents eviscerated soft rock.
Likewise, those who rival for Israel's leadership feel they are fighting an unstoppable force.
The last election with no winner led to an "emergency coalition" to fight the pandemic. Mr Netanyahu's rival Benny Gantz - a former general and political novice - agreed to a rotating premiership.
But Mr Gantz never got to take his turn. The remnants of his Blue and White party are facing near wipe-out, according to opinion polls.
'Guardian of Israel'
The drive back into town passes the only shopping centre. There's a queue at the shawarma restaurant. Others sit inside a franchise coffee shop, masks on. Business is also back by the crater.
Rachel Amsalem lives on the edge. Her home close to the clifftop is covered in Israeli flags.
A Likud cap rests on a rail in the porch, ready for outings when she faces off against the "black flag" protesters who oppose Mr Netanyahu.
"He doesn't sleep. He is the guardian of Israel," says Mrs Amsalem, borrowing a biblical phrase.
She knew him decades ago, working as a maid in the Netanyahu family home in Jerusalem.
Her parents fled Algeria in the 1940s. Decades later, she came to Mitzpe Ramon, a development town providing low-cost homes for Jewish immigrants, many from Arab countries. The community now forms a base of working-class support for Mr Netanyahu.
Mrs Amsalem credits him with the speedy vaccine deal helping bring the pandemic under control. Last year, her daughter-in-law, also called Rachel, died with Covid-19.
"Nobody else has the courage to pick up the phone and call [vaccine-maker] Pfizer," she says.
"He works day and night, whether it's [the diplomatic deals] with Arab countries, [countering] Iran, on corona, on the economy… there's one person we should say thanks to."
But Mr Netanyahu's opponents have instead been scrambling to find another viable challenger to him.
The "anti-Bibi" bloc now includes a former ally-turned-rival, Gideon Saar, who left Likud. Many more opposition votes are being soaked up by the centrist party led by a former TV host, Yair Lapid.