The United States has quietly joined Israel in urging Arab leaders to reformulate their 2002 peace offer, in an effort to end the decades-long Middle East conflict, Arab diplomats said Thursday. But so far, some Arab heavyweights are publicly resisting the idea. Three Arab diplomats in different Arab capitals said Washington has been pressing for changes to make the offer in line with the "road map," a peace plan supported by the United States and other members of the so-called Quartet group. That plan calls for a two-state solution to the conflict but falls short of specifying border lines for the proposed Palestinian state. The American ideas were presented through different diplomatic channels, said the Arab diplomats, all speaking on condition of anonymity because they are not allowed to talk to the press. Earlier Thursday, Prime Minister Ehud Olmert said that Israel was willing to make "sweeping, painful and tough concessions" to encourage dialogue with its enemies. Olmert also said a dormant Saudi Arabian plan for a comprehensive Mideast peace could be a "convenient basis" for contacts between Israel and Arab moderates. He was speaking at an event commemorating volunteers for national service in Tel Aviv. In the middle of Olmert's speech an embarrassing moment ensued when a member of the crowd cut into the prime minister's words and shouted at him. "What are you doing to ensure that Eldad Regev, Udi Goldwasser and Gilad Schalit can celebrate the Pessah Seder just like you and me?" the man shouted to Olmert. "There is not a single day we are not dealing with the subject. We will explore any avenue. It usually takes years and we pay a high price to release prisoners. I hope this time will be different. I cannot elaborate on the subject," Olmert replied to the man. The Saudi plan calls for full diplomatic relations between the entire Arab world and the Jewish state in exchange for full Israeli withdrawal from the West Bank and east Jerusalem. Israel rejected it outright when it was first proposed in 2002, and hardened its opposition after the Arab League tacked on an addendum endorsing the right of Palestinian refugees and their descendants to return to homes in Israel. But with recent meetings between Olmert and Palestinian President Mahmoud Abbas yielding sparse results, Israel has begun showing tentative interest in the plan. Arab countries are expected to revive the proposal at a summit later this month in Riyadh, Saudi Arabia. The push to reinvigorate the Saudi plan comes at a time when many moderate Arab governments are worried about rising tensions in the region and view progress on the Palestinian-Israeli issue as a way to defuse frictions and blunt Iran's growing influence.