Israeli Prime Minister Ariel Sharon's office says formal negotiations aimed at creating a broad-based unity government are set to start on Sunday.
Mr. Sharon has asked the main opposition Labor party, the small but influential ultra-orthodox United Torah Judaism party and another religious party, Shas, to meet with him.
The formation of a new government could help secure parliamentary approval of the prime minister's plan to withdraw from the Gaza Strip and parts of the West Bank next year.
Mr. Sharon has warned critics within his Likud Party that he could call early elections if they try to block the creation of a unity government and prevent implementation of his disengagement plan.
The prime minister received Cabinet approval of his plan earlier this year but some ministers from right-wing factions resigned in protest. As a result, Mr. Sharon lost his parliamentary majority. There are even members of his own Likud Party who oppose the disengagement plan and are vowing to do everything in their power to keep it from being implemented.
Labor Party leader Shimon Peres told Israel Radio Wednesday that his party would insist on two things, disengagement from the Gaza Strip and what he termed social justice.
Tuesday night Labor Party leaders gave its formal approval to Mr. Peres' plan to begin negotiations on joining the Sharon government. Mr. Peres says he is not certain the talks will be successful.
Some Labor Party members say they doubt Mr. Sharon's sincerity about following through with the Gaza disengagement plan. They point to his invitation for the Shas party to begin negotiations on joining the government as proof since Shas has rejected any dismantling of Jewish settlements in Gaza.
The negotiations on forming a new government are expected to take several weeks.