Israel's security cabinet is expected to meet Saturday night to declare a cease-fire in Gaza and will keep its forces there in the short term while the next stage of an agreement with Egypt is worked out. "It looks as if all the pieces of the puzzle are coming together," Mark Regev, a spokesman for Prime Minister Ehud Olmert, said Friday. "There will be discussions tomorrow morning, and it looks like a cabinet meeting will take place tomorrow night. Everyone is very upbeat." The most promising element for bringing the three-week conflict to a close occurred in Washington on Friday, where Secretary of State Condoleezza Rice and Foreign Minister Tzipi Livni of Israel signed an understanding on a range of steps the United States would take to stem the flow of new arms to Hamas from the Egyptian Sinai, mostly via tunnels. The agreement came on the last business day of the Bush administration and set the stage for the Obama administration to play a more active role in resolving the Arab-Israeli conflict. President-elect Barack Obama and Secretary of State-designate Hillary Rodham Clinton signed off on the plan, the State Department said. Whether Hamas will comply with the terms of parallel talks with Egypt was unclear. At a meeting organized by Qatar, a top exiled Hamas leader rejected Israeli terms for a cease-fire and called for increased resistance. "Israel will not be able to destroy our resistance, and the United States will not be able to dictate us their rules," the leader, Khaled Meshal, said in defiant remarks broadcast worldwide. "Arab countries should help Hamas to fight against the death of civilian Palestinians." But the Gaza branch of Hamas, squabbling with exiles out of the line of Israeli fire, seems to have agreed to much of Egypt's cease-fire proposal. Fighting in Gaza continued Friday, despite the apparent progress toward ending it. Palestinian medical officials said the death toll had risen above 1,100 people, many of them civilians. The cease-fire under discussion is more formal than the one that broke down late last month, when each side accused the other of failing to live up to its terms, and in some ways seems devised to overcome the last one's weaknesses. After meeting with Ms. Rice, Ms. Livni, who has been hawkish on continuing the assault aimed at stopping Hamas rockets from coming into Israel, stressed that the nation had met its war aims and was prepared to enter a cease-fire cautiously. "Israel embarked on the campaign in order to change the equation and restore its deterrent capacity," she told Israel Radio. "We did that a few days ago, in my opinion. It has to be put to the test. If Hamas shoots, we'll have to continue. And if it shoots later on, we'll have to embark on another campaign." The Bush administration agreed to the deal after consulting Mrs. Clinton and Gen. James L. Jones, who will be Mr. Obama's national security adviser. Ms. Rice discussed the terms over lunch with Mrs. Clinton on Thursday, the State Department spokesman said, and briefed Mr. Obama by phone. "It's safe to assume that we wouldn't have moved forward if we hadn't done some careful consultations, prior to signing, with the incoming folks," the spokesman, Sean McCormack, said. The timing of the agreement, after a last effort of American diplomacy, struck some Middle East experts as symbolic of a Bush administration that had refused to engage in the peace process until late in its term, and has left its successors with little choice but to re-engage. "They will inherit this agreement, which is critically important and will make them more engaged in the region than Bush was," said Aaron David Miller, a public policy analyst at the Woodrow Wilson International Center for Scholars. "This is the shape of things to come." Ms. Rice said the agreement was only supportive of broader negotiations being carried out by Egypt, and she refused to say when a cease-fire could actually take place and when the fighting in Gaza would stop. "We are doing everything we can to bring it to an end," she said.