WASHINGTON — The Obama administration has its Iran ducks in a row: Tehran is coming to the table, Israel is sitting still, most of the world’s major oil buyers and sellers are on board with the sanctions effort, and Congress is in an agreeable mood.

Ducks, though, have a tendency to wander off. Iran might not stay at the table, or it might offer delaying tactics that peel off support for sanctions by U.S. allies. Israeli leaders are skittish about alleged Obama administration leaks that they believe are aimed at heading off an Israeli military response. Republicans in Congress, while pleasantly surprised at the administration’s diligence at keeping to the sanctions timeline, are worried that the administration could offer too much at the talks.

Iran is not likely to deliver the concessions that the United States is likely to seek, said Alireza Nader, an Iran analyst at the Rand Corp., a think tank that often consults with government.

“The issue between Iran and the United States is not the nuclear program,” he said. “There is a perception among Iran’s leaders that Iran is engaged in a conflict with the United States and the nuclear program is part of the conflict. They believe that if Iran makes compromises under pressure, it makes Iran looks weak.”

Iran is ready for talks in Istanbul on April 13 with the world’s major powers, including the United States, on its nuclear program. It is not clear what the U.S. bottom line is, but Obama administration officials repeatedly have said that they will not ease the sanctions until Iran meets criteria set by the U.N. Security Council to make its nuclear program transparent.

The U.S. demands, according to reports, are that Iran stop enriching uranium to the 20 percent level. That figure is short of the 85 percent enrichment level needed for weapons grade, but it is close enough to raise concern. The U.S. also will reportedly demand that Iran shut down its underground nuclear facility near Qom.

The United States would allow Iran to enrich uranium to 3.5 percent for medical purposes, according to the reports, and would agree to put a stop on planned new sanctions in the congressional pipeline that would further isolate Iranian financial institutions.

That approach would not be enough to keep the Iranians at the table, according to Trita Parsi, the director of the National Iranian American Council, and it could push away major powers that until now have followed the Obama administration’s lead.

“This package is a non-starter to most observers, including to other P5+1 diplomats,” Parsi wrote on The Huffington Post, referring to the grouping of nations that negotiates with Iran on nuclear issues and comprises permanent U.N. Security Council members United States, Russia, China, France and Britain as well as Germany. “The problem is not necessarily the demands but the imbalance between what is demanded and what is offered.”

Dennis Ross, Obama’s former top Iran adviser who still consults with the White House, suggested last week that the U.S. might soften one critical additional piece of the sanctions should Iran comply with the demands on the Qom site and enrichment.

“If Iran were to stop enriching uranium to 20 percent, ship out the material it has already enriched to that level and deactivate the Fordow facility near Qom, that would probably be sufficient,” he said in an analysis distributed by the influential Washington Institute for Near East Policy think tank, where he now works. “Here again, the question is what Iran would seek in return. Lifting the Central Bank sanctions would probably be the minimum it would require.”

That prospect alarms Republicans in the U.S. Senate who until now have been impressed with Obama’s implementation of the sanctions regime.

“So far the Obama administration is completely faithfully implementing” the sanctions, said a Republican Senate aide involved in the sanctions legislation talks. “They’re executing everything as they’re supposed to.”

The Senate aide referred particularly to the president’s March 30 determination that oil markets could withstand U.S. sanctions that would effectively force much of the world to choose between cutting off Iran’s Central Bank and its energy sector or not dealing with the United States.

That effectively set the sanctions in motion and earned Obama some leeway in Congress for concessions he could make to the Iranians — but they would have to come after the Iranians had verifiably shut down their suspected nuclear weapons program, the Senate aide said.

“The idea that you have minimized a nuclear weapon by keeping them at 20 percent and not touching Natanz,” the aide said, referring to another enrichment facility, “that in no way stops the danger and would not change the calculus in Jerusalem.”

Republicans — and likely some Democrats, as well — would be “looking for a full suspension of all enrichment capabilities,” the aide said.

Israeli Prime Minister Benjamin Netanyahu, who met last month with Obama, told the White House and congressional leaders that he had not yet come to a decision on whether to strike, and would hold off while he assesses how Obama’s diplomacy and sanctions regime are working.

The pledge appears to be holding, although Israeli government officials have leaked to Israeli media their displeasure with what they see as Obama administration leaks about Israel’s capacity to strike Iran. Among the revelations that have alarmed Israeli officials was a story in Foreign Policy last month that reported on alleged Israeli dealings with Azerbaijan, as well as American intelligence speculation that Israel planned to use the Caucasus nation as a refueling ground for a strike.

The aims of the leaks campaign “are fully operational,” Ron Ben Yishai, a senior military analyst with deep Israeli government sources, wrote in Yediot Achronot, “to make it more difficult for Israeli decision-makers to order the IDF to carry out a strike, and what’s even graver, to erode the IDF’s capacity to launch such strike with minimal casualties.”

A White House insider denied that the leaks were part of a campaign, noting that rogue leaks from the intelligence community have been commonplace under multiple administrations.

Ron Kampeas is JTA’s Washington bureau chief.