US Secretary of State John Kerry left the Middle East on Monday without the framework agreement that he has been promoting as an interim solution to the Israeli-Palestinian conflict, but buoyed by the knowledge that he obtained Saudi backing for his peace push.

Earlier in the day Kerry met with Tony Blair, who serves as special envoy for the Quartet of Regional Peacemakers comprising the United Nations, European Union, United States, and Russia, AFP reported. The top US diplomat also convened with the leader of the Israeli opposition, Labor MK Isaac Herzog.

Herzog said he assured Kerry that the majority of the Knesset, including the opposition, supports reaching a diplomatic solution but that ensuring security and the rejection of the Palestinian right of return are central issues.

“I stressed that we see the utmost importance in the security arrangements that will ensure Israel’s ability to protect her citizens and the prevention of the right of return of Palestinian refugees to Israeli territory,” Herzog said.

Kerry spent Sunday jetting around the Middle East and attempting to shore up support for a US framework plan for Israeli-Palestinian peace, calling the endeavor a challenge that could still fall apart.

Kerry, meeting in Saudi Arabia with King Abdullah, said Riyadh would back American efforts to reach a deal between the sides.

“I am grateful that the Arab League as a whole and Saudi Arabia individually will be significantly involved in helping build support for this effort,” Kerry said at the Riyadh airport prior to his departure. “Today his majesty was not just encouraging, but supported our efforts in the hopes that we can be successful in the days ahead.”

Kerry said after his meeting with the Saudi leader that Abdullah’s 2002 initiative “has been part of the framework that we’ve been piecing together — both in inspiration and substance.”

The Saudi leader developed an initiative in 2002 in which the Arab world offered comprehensive peace with Israel in exchange for a full pullout from all territories it captured in the 1967 Mideast war.

The initiative, revolutionary when it was introduced, has been endorsed by the Arab League and, technically, remains in effect.

“Saudi Arabia’s initiative holds out the prospect that if the parties could arrive at a peaceful resolution, you could instantaneously have peace between the 22 Arab nations and 35 Muslim nations, all of whom have said they will recognize Israel if peace is achieved,” Kerry said.

“Imagine how that changes the dynamics of travel, of business, of education, of opportunity in this region, of stability. Imagine what peace could mean for trade and tourism, what it could mean for developing technology and talent, for job opportunities for the younger generation, for generations in all of these countries,” Kerry said.

Earlier on Sunday, Kerry flew to Amman, Jordan, and held more than an hour of talks with King Abdullah II and Foreign Minister Nasser Judeh. In addition to discussing the Israeli-Palestinian peace talks, Kerry reportedly raised other regional issues, including the civil war in Syria, increasing unrest in Iraq, and the Iranian nuclear program.

In a press conference held in Jerusalem on Sunday morning, Kerry called his trip “a productive couple of days with very, very intensive talks.” He also said that both Palestinian Authority President Mahmoud Abbas and Prime Minister Benjamin Netanyahu had made “important… and courageous decisions, difficult decisions,” but declined comment on the content of those decisions.

Speaking in Jerusalem on Sunday, Kerry likened the bid, to reach a historic deal between Israel and the Palestinians, to an enigma.

“In the end, all of these core issues fit together like a mosaic, like a puzzle and you can’t separate out one piece or another,” he said, adding that “the last pieces may decide to fall into place, or may fall on the floor, and leave the puzzle unfinished.”

Kerry met several times over the long weekend with Netanyahu and Abbas, seeking to finalize a framework deal covering all the core elements of a potential peace treaty, and is set to return later in the month to continue the effort. He is reportedly urging Netanyahu to continue talks on the basis of the pre-1967 lines with adjustments, and urging Abbas to recognize Israel as a “Jewish state.”

Beyond these points, too, the two sides are said to be at odds over most aspects of a permanent accord, notably including security arrangements, border demarcations, the fate of Jerusalem and Palestinian refugee demands. There have also been disputes over who will be released in a final phase of prisoner releases by Israel of terror convicts. And it is unclear whether the Palestinians are prepared to extend the current talks beyond their scheduled expiry date in late April.

As of yet, no confirmed concrete details of the framework agreement proposed by the US have come to light.