A senior Israeli minister said Monday that his country hoped to reach agreement with the Palestinians on a “declaration of principles” for peace by the end of the year, but not on a detailed peace treaty.

The comments by Haim Ramon, a vice prime minister and a close ally of Prime Minister Ehud Olmert, stated publicly what Israeli officials have said quietly for weeks now — that negotiating a final peace treaty this year with the Palestinian president, Mahmoud Abbas of Fatah, would be extremely difficult. They say that Mr. Abbas does not have the power to put a treaty into effect and that too detailed a treaty would also be likely to bring down Mr. Olmert’s government.

Already, Shas, a religious party in Mr. Olmert’s coalition, has warned that as soon as talks begin on how to divide Jerusalem, the party will leave the government. On Monday, the Shas chairman, Eli Yishai, said his party would leave if negotiations proceeded while rockets continued to be fired into Israel from Gaza.

“If there is any diplomatic progress in the negotiations with Palestinians beyond the current situation, and we are still under fire from Qassams and West Bank incidents, Shas will quit the government immediately,” Mr. Yishai said.

President Bush said last month on a visit here that his goal was to get both sides to sign a peace treaty before his term ends next January, and Mr. Abbas has said that a peace treaty by the end of the year is his goal. But Mr. Ramon said that he spoke to Mr. Bush during that visit and that Mr. Bush’s expectations were in line with Israel’s.

“I believe President Bush is not expecting a Palestinian state to be established by the end of the year,” Mr. Ramon said. “A declaration of principles will lead to a Palestinian state. It has to be detailed enough in order to implement it in the years that will come after 2008, two to three years after.”

The Bush comments had been greeted with some concern even by Palestinians aligned with Mr. Abbas and his appointed prime minister, Salam Fayyad. They worry that Mr. Abbas, Fatah and Mr. Fayyad, an independent, will all suffer politically if no peace treaty emerges.

Mr. Ramon said a declaration of principles would be much more detailed than the 2003 “road map” for peace. A declaration, he said, “will have to say what will be in Jerusalem, but not all the details.” If such a declaration can be negotiated, despite the threats from Shas, Mr. Ramon said, he expects the government to resign and to take the deal to the voters.

David Baker, a spokesman for Mr. Olmert, said: “If anyone doubts Israel’s sincerity, they’re mistaken. We are striving to get as far as we can. It should be clear to everyone that Israel is quite sincere about making progress.”

Mr. Ramon also spoke in tough terms about Gaza, saying that the government’s prime responsibility was to protect the Israeli citizens of Sderot, a town near Gaza that has borne the brunt of the rocket attacks, not to worry about the prosperity of Gaza, which is ruled by Hamas. He said Israel would defeat “the terrorist Hamas regime in Gaza” through military and economic pressure. “It will not happen in another two days, or in another two weeks, but we will bring about a solution to the Qassam rocket fire.”

The defense minister, Ehud Barak, said the army would take “any necessary step to return peace and security to the citizens of Sderot.” Israelis have been moved by the Twito brothers, Osher and Rami, who were seriously wounded on Saturday night when a Qassam rocket exploded near them in Sderot, as they stood at a cash machine to get money to celebrate the birthday of their father, Rafi.

Osher, 8, had his left leg amputated and was operated on again on Monday, and remains in intensive care on a ventilator, while Rami, 19, underwent an operation on Monday for breaks and shrapnel wounds to his legs, said Michal Shabtai, speaking for Sheba Medical Center in Tel Aviv. Both boys will have further operations.