The Israeli Labour Party leader has increased pressure on Prime Minister Mr Ariel Sharon by advocating early elections a day after the Likud party barred Mr Sharon from coalition talks.
Mr Shimon Peres effectively closed the door to further talks with Mr Sharon, who needs the centre-left party to push through his Gaza pullout plan but left open the possibility of future negotiations should an unlikely majority in Labour agree.
Mr Sharon had vowed to press ahead with the Israeli withdrawal from the Gaza Strip despite a humiliating rebuff from Likud that voted on Wednesday against bringing Labour into the government.
Mr Peres, a strong proponent of ceding occupied land for peace, said he would continue to support the Gaza pullout but suggested Mr Sharon had been too seriously weakened by the revolt of Likud rightists to pursue talks with the main opposition party.
"The opinion of the Labour Party today is to call for new elections and allow the people to decide," Mr Peres, a veteran former prime minister and foreign minister, told journalists.
He said elections, which do not have to be held until 2006, should take place "as soon as possible, the minute there is a majority in the Knesset," Israel's parliament.
Mr Peres needs a two-thirds majority to dissolve the 120-seat parliament, which is in recess until October, and some Labour lawmakers voiced doubts they could win such a vote.
There was no immediate comment from Mr Sharon, but sources close to the premier said that although he wanted to avoid early elections he could not rule them out.
Early elections would almost certainly delay the evacuation of 8,000 Jewish settlers from Gaza and hundreds from four West Bank settlements next year under Mr Sharon's pullout plan.
Polls show most Israelis support the withdrawal, regarding the coastal Gaza Strip as a bloody liability. Likud rebels argue that abandoning any land Israel captured in the 1967 Middle East war would "reward Palestinian terrorism".