WASHINGTON — Two weeks before their launch, the promised renewal of Israeli-Palestinian peace talks has already engendered a first: a joint statement of welcome by mainstream U.S. Jewish and Palestinian groups.

“We congratulate the Obama administration on succeeding in getting direct negotiations back on track,” said a statement issued jointly on Friday by the Jewish Council for Public Affairs and the American Task Force on Palestine.  “Both parties must now show courage, flexibility and persistence in order to move towards a negotiated end of conflict agreement.”

Other than its joint letterhead, the document was mostly unremarkable — as were many of the reactions to the announcement — in part, because Jewish leaders were endeavoring to make sense of the vague outline of the proposed talks. The terms of the talks, set to begin Sept. 2, have yet to be determined, including whether and how the sides will discuss final status issues, such as borders, Jerusalem and refugees.

In an off-the-record conference call with top White House staff just before the Sabbath on Friday, Jewish leaders pressed for details: Is there a deadline? Will there be preconditions? In response, according to people on the call, they got little more than the vague back-and-forth that had characterized the announcement of the talks earlier in the day by Secretary of State Hillary Rodham Clinton.

How often would the lead parties to the talks, Israeli Prime Minister Benjamin Netanyahu and Palestinian Authority President Mahmoud Abbas, meet, one participant asked — and how often would the teams meet?

“Periodically,” Dennis Ross, Obama’s top Iran policy official said, referring to the leaders. “Regularly,” he said of the negotiating teams.

Dan Shapiro, the top National Security Council staffer handling Israel and its neighbors, broke in to add that the talks would be “intensive.”

What about the yearlong time frame announced by Clinton and the top Middle East envoy, George Mitchell, another Jewish leader asked. Was that a deadline? A goal?

“Feasible,” said David Hale, Mitchell’s deputy. A year was the “objective.”

What about the U.S. role?

“Very active,” said Hale. But then: “We will need to play a role, but they still need direct talks.”

Much was made by the administration officials of the dinner that is to take place Sept. 1, bringing together President Obama, Netanyahu, Abbas, and the Jordanian and Egyptian leaders. “The dinner will help to restore trust,” Ross said.

Administration officials have suggested that the outlines will be clearer after Netanyahu, Abbas and Clinton meet on Sept. 2.

P. J. Crowley, the State Department spokesman, told reporters Monday that extending Israel’s partial moratorium on settlement building would be on the agenda that day. Abbas has threatened to quit the talks without such an extension.

“The issue of settlements, the issue of the moratorium, will be – has been  – a topic of discussion and will be a topic of discussion when the leaders meet with Secretary Clinton on Sept. 2,” he said.

Rabbi David Saperstein, director of the Religious Action Center of Reform Judaism, who has been closely tracking the Israeli-Palestinian diplomatic process, said he is confident that with months of indirect talks behind them, the leaders would be able to come up with a coherent outline for the direct negotiations.

“If there isn’t total clarity about the ground rules yet, there surely will be before Sept. 2,” Saperstein said. “They bring months and months of talks behind the scenes that will make a major contribution.”

Seymour Reich, a former chairman of the Conference of Presidents of Major American Jewish Organizations, wondered nonetheless if the sides were prepared for success. If the talks work out, he said, Netanyahu and Abbas would have to pitch major compromises to skeptical constituencies — Netanyahu to the hard-liners who support him in government, and Abbas to a Palestinian electorate he hopes to wean away from Hamas, the terrorist group that continues to seek his ouster.

“You sometimes get what you wish for,” Reich said, referring to Netanyahu’s vocal insistence for months on direct talks. “But then you’ve got to put up or face the consequences.”

Given the vagaries surrounding the proposed talks, it was no surprise that the response from organizations was as noncommittal as the Obama administration’s announcement, focusing principally on the benefits of face-time.

“Sitting together, face-to-face, leader-to-leader, in direct negotiations is the only path to achieving the ultimate goal of peace, reconciliation and the end of all claims,” AIPAC, the American Israel Public Affairs Committee, noted in a statement.

That message was echoed by the Conference of Presidents of Major American Jewish Organizations: “We welcome the beginning of direct, face-to-face negotiations between Israel and the Palestinian Authority that will address the complicated and difficult issues in the hope of bringing about an end to the long-standing conflict.”

There were subtle indications among the statements of how groups might act should the talks take off — or should they break down. AIPAC made clear whom it would blame if such a breakdown occurs: “For talks to succeed, the P.A. must match Israel’s commitment to conducting peace talks without preconditions or excuses, abandon its longstanding attempts to avoid making difficult choices at the negotiating table, and cease incitement against Israel at home and abroad.”

The joint statement by the American Task Force on Palestine and the consensus-driven Jewish Council for Public Affairs was more careful to balance responsibility between both sides. “Both sides must take concrete steps in the short term to instill greater mutual confidence in this process and to demonstrate resolve to stay at the negotiating table as long as it takes to achieve an agreement,” the statement said.

On background, Jewish organizational leaders said that the talks — at their launch, at least — were so vaguely defined that top pro-Israel officials would not even consider cutting short their pre-Labor Day vacations in order to meet with Netanyahu when his team arrives on Sept. 1.