Prime Minister Benjamin Netanyahu's right-wing Likud party has won a surprise victory in Israel's election, Israeli media report.
Earlier exit polls had suggested a dead heat with centre-left Zionist Union.
With most votes counted, Likud is said to be on course to take 29 seats in the 120-seat parliament, the Knesset, with the Zionist Union on 24 seats.
If confirmed, this would indicate another coalition government led by Mr Netanyahu.
Mr Netanyahu would need support from other parties to form a coalition.
In a speech to his jubilant supporters in Tel Aviv after Tuesday's polls closed, Mr Netanyahu said he had already spoken to the leaders of other right-of-centre parties about forming a new government "without delay".
Speaking after the exit polls were published, Zionist Union leader Yitzhak Herzog told his supporters he was confident of forming the next government.
"We have achieved an unbelievable achievement today.
"I will do all that I can in order to create a real socially minded government for Israel."
When final results are known, President Reuven Rivlin will give the task of forming a government to a party leader who he thinks has the strongest chance of assembling a coalition.
Israel's form of proportional representation always produces smaller parties and coalition government, the BBC's Middle East editor Jeremy Bowen in Tel Aviv reports.
Mr Netanyahu could become Israel's longest-serving leader if he secures a fourth term.
No party has ever won an outright majority under Israel's proportional representation voting system.
Almost 72 percent of those eligible voted in the election, which ended at 22:00 local time (20:00 GMT). The turnout was four points higher than the previous election in 2013.
Israel's Channel 1 and Channel 10 both projected 27 seats each for Likud and Zionist Union, while Channel 2 gave Likud a one-seat lead, with 28 seats.
61 seats are needed in order to secure a majority.
The Joint Arab List, an alliance of Israeli Arab-dominated parties, has come third with about 13 seats, the exit polls suggested.
It has said, however, that it will not take any positions in government.
Mr Netanyahu had vowed not to allow the creation of a Palestinian state if he wins a fourth term, while Zionist Union has expressed support for a two-state solution and promised to repair relations with Palestinians and the international community.