An absence of progress on the core issues, an ill-timed Israeli announcement of plans to build hundreds more housing units in East Jerusalem and the West Bank, and grousing by Israeli and Palestinian officials about each other’s motives are contributing to a sense that the negotiations are sputtering, like so many previous efforts to bridge the gaps between the two sides.

“He is trying to give a push,” said a senior American official, who spoke on the condition of anonymity because of the delicacy of the matter, adding that the talks were bogging down “both because of short-term irritants and slowness at getting at fundamental issues.”

Mr. Kerry was a tireless prod and a frequent presence in Jerusalem and Ramallah leading up to the resumption of talks on July 30, and he has more recently met for hours at a time with Prime Minister Benjamin Netanyahu of Israel and the Palestinian president, Mahmoud Abbas, in neutral sites like New York, London, and Rome. Now, after a brief period of withdrawal to deal with other problems, he is returning to the region to throw himself back into the process.

His back-and-forth schedule bears all the hallmarks of shuttle diplomacy. Mr. Kerry is to meet Mr. Netanyahu here on Wednesday morning, then to drive to nearby Bethlehem, on the West Bank, to sit down with Mr. Abbas, before returning for dinner with Mr. Netanyahu. Mr. Kerry will circle back with Mr. Abbas in Amman, Jordan, on Thursday evening.

American officials have disclosed little about the details of the talks, though the senior official said that negotiations over Israel’s security and the economic development of the Palestinian-administered West Bank had emerged as bright spots in the discussions.

Until this week, Israeli and Palestinian officials had honored a pledge not to publicly discuss the internal discussions to avoid poisoning the atmosphere. But the first cracks in that facade have appeared, with Mr. Abbas bemoaning the lack of results in a speech and a senior Israeli official accusing the Palestinians of not negotiating in “good faith.”

The public criticisms from Mr. Abbas, in particular, complicate Mr. Kerry’s task, according to former diplomats, by raising the pressure on him to produce results on an accelerated timetable, which in turn could strain his relationship with Mr. Netanyahu.

“After all these rounds of negotiations, there is nothing on the ground,” Mr. Abbas said in a speech Sunday to officials of his Fatah Party. “The negotiations are still without results.”

On Tuesday, the Palestinian leadership published a fact sheet asserting that Israel had “escalated announcements of illegal settlement activity” since the resumption of talks. It cited the new housing units in the West Bank and East Jerusalem, including more than 2,000 for which tenders had been published this week.

But an Israeli official brushed off the criticism of settlement construction from Palestinian leaders, saying “Israel has scrupulously honored the understandings that were reached at the beginning of the current round of talks.” Israel had warned Mr. Kerry it would continue to build in the settlements during the negotiations.

On Tuesday, Gideon Saar, Israel’s interior minister and a confidant of Mr. Netanyahu’s, accused the Palestinians “of trying either to isolate or to boycott the state of Israel while holding negotiations with it.”

“There is a total lack of flexibility in their opening positions,” he said.

Senior Israeli and Palestinian officials said that in meetings in Europe last month, Mr. Netanyahu and Mr. Abbas both warned Mr. Kerry that the talks were close to an impasse. “I think he was a bit shocked when he got the briefings,” a Palestinian official said.

A senior Israeli official agreed that Mr. Kerry wanted “to put more pressure on both sides.” This official also said the Obama administration had begun to realize it would likely need to present a framework for an agreement if the negotiations reach a “dead end.”

On Monday, however, Mr. Kerry denied reports in the Israeli news media that in the absence of any breakthrough in the next two months, the United States would offer its own plan to create a Palestinian state based on the borders before the Arab-Israeli war of 1967, with agreed-upon land swaps between Israel and the Palestinians.

“There is no other plan at this point in time,” Mr. Kerry said, choosing his words carefully in a clearly fluid situation.

For diplomacy watchers, the speculation about an American plan, while premature, indicates that the talks have progressed beyond their first phase, in which teams of negotiators chew over the issues, to a second phase, in which Mr. Kerry can be more directly involved in trying to find areas of agreement between Mr. Netanyahu and Mr. Abbas.

He will also brief Mr. Netanyahu about parallel nuclear negotiations with Iran, prompting analysts to suggest a possible link between the two. Mr. Netanyahu, they said, may be under pressure to accede to Mr. Kerry’s demands on the peace process in exchange for American vigilance on maintaining sanctions against Iran during the nuclear talks.

“The challenge is Kerry is that these talks aren’t yet ready for prime time,” said Aaron David Miller, a former Middle East peace negotiator. “He needs to keep the radio silence going to avoid an escalatory public cycle of the blame game between Netanyahu and Abbas.”