After months of quiet U.S. diplomacy, Israeli and Palestinian leaders appear poised to announce a resumption of direct peace talks, perhaps as early as this week.

Nearly two years after the last round of talks broke off, U.S. and allied officials in recent days cleared the final hurdle by persuading Palestinian Authority President Mahmoud Abbas to take a seat at the negotiating table, officials say.

Catherine Ashton, the European Union's top foreign policy official, said in a letter to European officials Friday that Abbas might make an official commitment in the next few days to talks that could begin later this month.

The announcement will come as a relief for the Obama administration, which has had little to show for an 18-month slog on one of the president's top foreign policy priorities. Progress toward peace is viewed by Obama administration officials as key to building support in the Muslim world for other urgent U.S. goals, including the war in Afghanistan, and the effort to halt Iran's nuclear program.

Yet the talks will begin in an atmosphere of deep pessimism.

Though Israeli Prime Minister Benjamin Netanyahu has said he is ready to make "painful sacrifices" for peace, his government and the parliament, or the Knesset, may be among the most conservative in Israel. On the Palestinian side, Abbas' ability to deliver on an agreement is in question: The Hamas militant group, not his government, controls the Gaza Strip, where 1.5 million Palestinians live.

One measure of the pessimism surrounding the effort is the relative lack of attention that the approach of new, direct talks has received in the region.

Previously, for instance, the prospect of active negotiations would generate noisy demonstrations by Israelis worried about what their government would give up. This time, the protesters are staying home, analysts note.

Since May, the Obama administration has pushed "indirect talks," in which U.S. envoy George Mitchell has shuttled between the two sides. There has been little discernible progress.

The one wild card in the new talks is the American role. President Obama has signaled that his government is willing to take a more active role than did George W. Bush's administration, which was reluctant to push proposals on the Israelis.

The prospect has stirred hope among Palestinians, who feel Obama may have more sympathy for their cause, and anxiety among the Israelis, who fear the administration may pressure them for concessions that threaten their security.

Major issues, as in previous talks, will be the borders of a Palestinian state, Israeli security, the claims of Palestinian refugees and competing claims over Jerusalem.

Abbas has balked for weeks at officially joining the talks, arguing that he wanted agreement on some general principles, such as that Israel's 1967 borders would be a starting point for negotiations.

Israel contends talks should be held "without preconditions." Abbas fears that unless there is prior agreement on a basic agenda for talks, the Israelis could make unrealistic demands, then blame him for the breakdown.

If the negotiations get stuck, as is widely expected, the administration is expected to put forward some of its own proposals, and might even offer something like the package President Clinton laid out in 2000 to overcome differences. Administration officials say they will not be passive bystanders.

"The United States has played a special role in these kinds of discussions, and we're prepared to do that again," a senior administration official said in a recent interview.

But some people close to the discussions see signs that Obama may be undecided on what policy he wants to pursue.

Last year, Israeli and Palestinian officials said it was clear that Mitchell's statements reflected the president's choices. Now a variety of players with conflicting opinions are weighing in, including Secretary of State Hillary Rodham Clinton, Vice President Joe Biden, White House Mideast advisor Dennis Ross, and National Security Council Chief of Staff Denis McDonough.

The Israelis find the views of Ross reassuring, but are more uneasy with those of other National Security Council aides such as McDonough.

One issue that is sure to be tougher this time around is security. Israel worries that rockets and other arms could be smuggled into a new Palestinian state in the West Bank, as they have been smuggled into Gaza.

Any deal would probably require, among other security provisions, that Israeli forces be allowed to stay in the West Bank during an extended transition period to gather intelligence and keep an eye on smuggling.

"This would really be onerous for the Palestinians," said Steven J. Rosen, a former longtime official of the American Israel Public Affairs Committee. "These are issues of freedom of movement and sovereignty, and they're really insulting to the Palestinians."

But the Israelis would insist on such conditions, he said.

Elliott Abrams, a chief advisor to President George W. Bush on the Middle East, said he viewed the outlook for the talks as "dim" and wondered what Obama planed to do if they reached a dead end.

If there's little progress by the time an election season begins next year, Obama may ask himself: "What will it profit me to invest more in this for the next year and a half?" Abrams said. At that point, the president could downgrade the peace effort so that the envoy "goes out intermittently, and you make believe that you're still trying."

The senior administration official, asked about the administration's hopes, said that "we've been at this for a long time, and while we haven't found the magic formula, the issues are well known."

"We're not underestimating the degree of difficulty," he said. "But the only way to get to a final settlement is to try direct negotiations."