The official line in Washington, Jerusalem and Ramallah is that the decision by Prime Minister Ehud Olmert of Israel to resign will not affect American efforts to negotiate a peace deal between Israelis and Palestinians before the end of the year.

Israeli officials said Thursday that Mr. Olmert could still try to reach a peace pact in his remaining time in office. In Tunisia, Mahmoud Abbas, the Palestinian leader, pledged to work with Mr. Olmert and his successor.

And at the State Department, a senior administration official said that Secretary of State Condoleezza Rice was not ready to give up yet. “That decision point has not been reached,” the official said, speaking on condition of anonymity.

“Fundamentally, as Americans,” the official added, “we don’t give up.”

To that end, Ms. Rice told Palestinian and Israeli officials that she would return to the region in late August for more talks.

But that trip may be based mostly on wishful thinking, foreign policy experts said. For numerous reasons — most of them stemming from a murky political picture in Israel that will get even murkier as Mr. Olmert’s rivals jostle for power — the Bush administration’s efforts to mediate a peace deal between the Israelis and Palestinians this year are unlikely to bear fruit.

“It’s over,” said David Makovsky, an analyst with the Washington Institute for Near East Policy. “Rice was counting on the fact that Olmert’s dwindling political fortunes would lead him to turn to a diplomatic victory as a springboard toward a political comeback. But if he’s leaving office, that doesn’t happen.”

A few officials at the State Department expressed the slim hope that Mr. Olmert, now freed of the political shackles that make concessions so difficult, could turn his lame-duck status into an asset and strike a peace bargain with Mr. Abbas.

But even if Mr. Olmert were able to reach a deal on the four contentious “final status” issues that have bedeviled peace negotiators since 1979, he would be in no position to sell it to a skeptical Israeli public.

The chances of a deal that could be carried out on the ground were not great to begin with, foreign policy experts say. The authority of Mr. Abbas, Mr. Olmert’s negotiating partner, is confined to the West Bank. (The militant Islamist group Hamas seized control of Gaza a year ago.) Israeli officials say they fear that any security promises made by Mr. Abbas would not be honored by Hamas.

Added to that, Mr. Olmert told Israeli officials earlier this week that he did not see the status of Jerusalem as part of the peace deal this year and would rather postpone talks on that contentious issue. It is hard to imagine Palestinian authorities trying to sell an agreement that did not include Jerusalem to their already skeptical population.

“The bottom line: Can Olmert reach a half-baked agreement minus Jerusalem with Abbas and with Condi looking on proudly in the next several months? Maybe,” said Aaron David Miller, the author of “The Much Too Promised Land: America’s Elusive Search for Arab-Israeli Peace.”

“But can he sell it, let alone implement it, in an environment in which he has no popular support or moral authority, with Hamas threatening from the sidelines? No way.”

The Israeli politicians vying to succeed Mr. Olmert as the leader of the Kadima Party and perhaps as prime minister are unlikely to be enthusiastic about contentious negotiations with the Palestinians while campaigning for election, Israel experts said.

When the news of Mr. Olmert’s resignation broke on Wednesday, Ms. Rice was holding a three-way meeting at the State Department with one prime ministerial hopeful, Tzipi Livni, the Israeli foreign minister, and with Ahmed Qurei, the chief Palestinian negotiator. Ms. Rice nonetheless urged the two sides to work toward an agreement on at least the contours of a final peace before the end of the Bush administration, Israeli and Palestinian officials said.

“We’re pushing, prodding and cajoling,” a senior Bush administration official said. “They’re the ones who are negotiating, but our goal is still as stated: getting an agreement by the end of the year that addresses all the final status issues.”

The final status issues include the dismantling of Israeli settlements in the West Bank and agreeing on the borders of a Palestinian state, the status of Jerusalem and the fate of Palestinian refugees who left, or were forced to leave, their homes.

“There is zero chance” now, said Ghaith al-Omari, a former negotiator for Mr. Abbas. Mr. Omari said that the best the Palestinians could now expect was that Ms. Rice could manage to preserve something to hand to the next administration.

“The best we can hope for is a stabilization package that will make it easier for the next president to engage the process,” Mr. Omari said.