Clinton met for four hours longer than scheduled with Egyptian officials Wednesday, apparently unwilling to return to Washington without at least a framework for a deal.
President Barack Obama also played a key role, apparently providing the final push to get Israeli Prime Minister Benjamin Netanyahu to embrace the deal.
That push came in a phone call between the two men, with Obama recommending that Netanyahu accept the deal and Netanyahu responding positively to his recommendation to give a chance to the Egyptian proposal for a cease-fire, according to a statement from the prime ministers office.
Obama also spoke with Egyptian President Mohammed Morsi, congratulating him on the way his government handled the talks. The United States does not recognize Hamas, which it considers to be a terrorist group. Instead, Egypt, whose Muslim Brotherhood leadership is close to Hamas officials, served as a proxy for Hamas interests.
The seven-point agreement filled a single printed page. It called for Israel to stop all hostilities on the Gaza land, sea and air including incursion and targeting of individuals, an apparent reference to the Israeli assassination campaign against top Hamas leaders. It was just such an attack that started the current round of violence, an Israeli strike that killed the leader of Hamas military wing, Ahmed Jabari.
In return, all Palestinian factions shall stop all hostilities from the Gaza Strip against Israel including rocket attacks and attacks along the border.
Israel agreed to allow some goods to enter Gaza and for residents to leave after 24 hours, but the deal did not provide specifics.
In a news conference in Cairo, Hamas leader Khaled Mashaal claimed victory, saying that Israels assault in Gaza had succeeded only in destroying buildings and killing innocents, but it had not broken the will of the residents there.
He called Israel the aggressor and defended militants firing of rockets at Israeli cities. He also charged that the offensive was part of a political ploy by Netanyahu in the run-up to Israeli parliamentary elections in January.
We had to react, Mashaal said.
Israeli officials also claimed victory. Israeli government spokesman Regev said the agreements call for "complete and total cessation of all hostile activity initiated in the Gaza Strip" had achieved the goals that Israel had when it began its bombardment of Gaza.
"For us, thats victory. Thats what we wanted," he said.
In the meantime, Morsi spokesman Yasser Ali said Egypt would work with all parties to monitor the implementation of the cease-fire.
While Obama congratulated Morsi on the agreement, the process exposed what appeared to be factions within Egypts new government in its approach to Israel. Notably, Morsi, whose Muslim Brotherhood-backed constituency supports Hamas, did not announce the deal. And in the early days of this weeklong conflict, Morsi withdrew Egypts ambassador to Israel.
Western diplomats in Cairo said members of Morsis intelligence services, not representatives of the presidents office, shuttled between Israeli and Hamas officials to find a consensus.
Israeli officials said that there was also internal disagreement within the Israeli Cabinet over the cease-fire terms. While Netanyahu and Defense Minister Ehud Barak had argued that an oral agreement would be enough, other Cabinet ministers, including hawkish lawmaker Avigdor Lieberman, said that Israel must demand a deal on paper.
The Israeli Cabinet met late Tuesday night and again Wednesday, then rejected establishing a unilateral cease-fire.
There was international pressure for Israel to stop firing first, the idea being that Gaza would then be put under pressure by Egypt and others to stop firing as well, said one political official who took part in the Cabinet meeting but spoke only on the condition of anonymity. But the feeling was that there was not enough guarantee that rocket fire would stop from Gaza.
Special correspondents Mel Frykberg and Muhammad Shahin contributed to this report from Gaza City.