Benjamin Netanyahu, the man expected to be Israel’s next prime minister, has been given another two weeks to form a new government.
Under Israeli law, the leader of the right-of-centre Likud party has until early next month to form a coalition, following recent elections.
Mr Netanyahu has met President Shimon Peres to discuss the proposed make-up of his government.
He is trying to convince the Labour Party to join, correspondents say.
If he fails to do so, they say, he will be forced to form a narrow coalition with hard-line Israeli parties.
The two-week extension sets 3 April as Mr Netanyahu’s new deadline.
The centrist Kadima narrowly defeated Likud in the election held on 10 February, but Mr Netanyahu has the support of the religious and right-wing parties which make up more than half of Israel’s parliament.
During his meeting with Mr Peres, Mr Netanyahu reportedly said he needed the extension in order to try to form "a national unity government".
"The creation of such a government is all the more important in view of… the grave (security) threats and economic crisis," the president’s office quoted Mr Netanyahu as saying.
Mr Lieberman is a controversial figure because of his views on Israeli Arabs
Mr Netanyahu has said Israel faces "great challenges" including the global economic crisis and what he said was Iran’s wish to obtain nuclear weapons.
Earlier this week, the PM-designate signed his first coalition deal with Yisrael Beiteinu, which could see its leader, the controversial right-winger Avigdor Lieberman, becoming foreign minister.
But Mr Netanyahu has also been seeking the support of the centrist Kadima party.
If Kadima also joins the coalition line-up, party leader and current Foreign Minister Tzipi Livni could keep her position, although talks have so far proved inconclusive.
Ms Livni has demanded Mr Netanyahu signs up to a two-state solution with the Palestinians before she joins the government.
Yisrael Beiteinu is a strong supporter of Israeli settlement activity in the occupied West Bank, seen as illegal under international law and a major obstacle to a peace deal.
Mr Netanyahu favours a revised peace formula, which concentrates on economic development of autonomous Palestinian areas rather than agreeing territorial deals with the Palestinians.
If Kadima sees through its stated intention to lead the opposition, Likud is expected to try to bring in smaller hard-line parties like Jewish Home, National Union and United Torah Judaism.
That would give it a solid right-wing majority of 65 in the 120-seat parliament.
The deal with Yisrael Beiteinu envisages it getting five cabinet posts.
In addition to foreign affairs Mr Leiberman would be named deputy prime minister. Other posts include the ministers of internal security, infrastructure, tourism, and the immigrants integration.