Unofficial results in Israel's second election in five months suggest it is too close to call, Israeli media say.
Incumbent PM Benjamin Netanyahu's party and that of his main challenger, Benny Gantz, are neck and neck with 32 seats each, the Kan public broadcaster says.
A prime minister needs to command a 61-seat majority in parliament. The smaller Yisrael Beiteinu party appears to hold the balance of power.
Official partial results are expected on Wednesday morning.
Benjamin Netanyahu, Israel's longest-serving prime minister, has been in office for 10 years and is vying to win a record fifth term in office.
The 69-year-old, who leads the right-wing Likud party, has pledged to annex Jewish settlements and a swathe of other territory in the occupied West Bank if he is returned to power.
Palestinians, who seek a state in the West Bank and Gaza, with its capital in occupied East Jerusalem, have warned such a move will kill any hopes for peace.
Mr Gantz, who leads the centrist Blue and White party, has not advocated any form of annexation though his position on the creation of a Palestinian state is unclear.
Like Mr Netanyahu, he has ruled out ever dividing Jerusalem, which Israel considers its capital.
On Wednesday morning, Yisrael Beiteinu's leader Avigdor Lieberman, reiterated that he would only support a government comprising both Likud and Blue and White.
However, Blue and White has ruled out sitting with Mr Netanyahu in a coalition.
What are the latest results?
Official results have been slow to be released, with only 30% of votes counted by 09:15 (06:15 GMT).
They put Likud slightly ahead of Blue and White, with the ultra-Orthodox Shas party third and Yisrael Beiteinu fourth, but without indicating how this translates into seats in the knesset (parliament).
According to the Times of Israel, Kan is reporting unofficial results based on what it says is 96.9% of votes counted.