The Palestinian prime minister, Mahmoud Abbas, and several governments have pushed for the agreement, but President Bush warned today that a cease-fire was not enough. 

"It's one thing to make a verbal agreement," Mr. Bush told reporters in Washington. "But in order for there to be peace in the Middle East, we must see organizations such as Hamas dismantled."

Mr. Bush made his comments shortly after an Israeli helicopter fired two missiles at a Palestinian car in the Gaza Strip that the army said was packed with mortar shells to be fired at Israeli settlements. The attack killed two people, including a woman, who were described by Palestinians as bystanders. 

At least one Palestinian militant was wounded, among at least 16 others, Palestinian officials said. 

Calling the strike an attempted assassination of one of its members, Hamas officials in Gaza said that it would postpone any action on the proposed cease-fire. They also said they were still awaiting guarantees from Egypt that Israel would not continue to single out its members. The European Union has also pressed for a cease-fire.

The Israeli airstrike came after a day of chaotic violence. Earlier, two Hamas gunmen were killed when they attacked an Israeli post in the northern Gaza Strip, in the town of Beit Hanun. Hamas fired at least one crude rocket over the Gaza boundary at the Israeli town of Sederot, injuring no one. 

In the Israeli Arab town of Kfar Qasem, in central Israel near the West Bank boundary, the police found and destroyed what they described as a large bomb. They said they had arrested two suspects.

Israeli officials reacted with scorn to the Palestinian condemnation of the the missile attack. "So, what, we have to let them launch rockets because Hamas and Islamic Jihad are negotiating a camouflage cease-fire?" asked Gideon Meir, the deputy director general of the Israeli Foreign Ministry. 

Israeli officials say they fear that a cease-fire will only allow militants to rearm. They were delighted today with President Bush's remarks. 

Palestinian officials accused Israel of seeking to scuttle the cease-fire with a series of missiles strikes and military raids as talks progressed among Palestinian factions in recent weeks. But Qadoura Fares, a Palestinian legislator involved in the talks, said tonight that an agreement could come as soon as Thursday. 

"There will be an agreement," he said. "Of course, the attack in Gaza affected the atmosphere." He added, "We want the declaration to be in a calmer climate."

The precise details of the agreement are not known, but Mr. Abbas has said that he wants to end the armed uprising and put a stop to "terror against the Israelis wherever they might be." But Mr. Abbas has endorsed a two-state solution to the conflict, while Hamas has rejected Israel's right to exist and any negotiation with the Jewish state.

More than the substance of the agreement, he said, officials were now debating how to make the announcement. He said that it might be made in Cairo or else in the occupied territories of the West Bank and Gaza Strip, and that a delegation of the factions might then present the agreement to Mr. Abbas.

Hamas leaders in the Gaza Strip continued today to question the value of a cease-fire. But this deal appears to have been negotiated primarily with Khaled Mashal, a top Hamas leader based in Damascus, Syria.

Last week, Mr. Fares carried a message to Mr. Mashal and to a leader of Islamic Jihad, Ramadan Abdullah Shallah, from Marwan Barghouti, a popular leader of the mainstream Palestinian faction, Fatah. He urged the other factions to accept the cease-fire, saying that it would demonstrate to the world that Palestinians were not the obstacle to peace in the Middle East. 

Mr. Barghouti is being held by Israel on charges of terrorism, which he denies. He appears to be passing messages through his lawyers, one of whom was seen in Mr. Fares's office in Ramallah, in the West Bank, on Tuesday, preparing for a meeting today with the jailed leader.

Mr. Mashal is now in Cairo for final talks on the deal, officials said. 

A new international peace plan, known as the road map, calls on the Palestinian leadership as a first step to begin "dismantlement of terrorist capabilities and infrastructure." Israel is supposed to reciprocate simultaneously by refraining from "attacks on civilians" and demolitions of Palestinian homes, and by taking steps against settlement growth in the West Bank and the Gaza Strip.

Mr. Abbas has sought a cease-fire to avoid using force against Hamas, believing he lacks political support for that move before he makes any substantive gains in talks with Israel. But he plans in the longer term to take steps like collecting illegal weapons, his allies say.

The talks with Israel remained stalled today, with each side blaming the other. Officials on both sides continued to say they remained close to an agreement for Israel to begin returning security responsibility to the Palestinian Authority for areas that by previous agreement are supposed to be under Palestinian control. They are planning to start with the West Bank city of Bethlehem and parts of the Gaza Strip. 

Some officials speculated today that the adversaries were postponing announcements of substantive progress in anticipation of the arrival here this weekend of Condoleezza Rice, Mr. Bush's national security adviser, on her first visit to oversee action on the new peace plan. Both sides regard her as Mr. Bush's personal envoy, and they are eager to make a good impression.

"They're waiting for Condi," one Palestinian official said.

The official said of the cease-fire talks and the negotiations with Israel, "Everything is far too close on both tracks for it to all collapse, but that doesn't mean that any agreement we get with the Israelis isn't going to collapse."