Hopes the new and indefatigable Secretary of State John Kerry could charm Israel and the Palestinians back into talks are fading at the edges as months pass with no sign of a breakthrough, analysts say.

True, the top US diplomat has visited the region four times since coming to office in February, and he has also been warmly received and on the whole spared the usual insidious whispering campaigns in the local media.

Kerry himself points to a perceived slow-down in Israeli settlement building as a positive sign that Prime Minister Benjamin Netanyahu is serious about peace, and he has also cited restraint by the Palestinians in pursuing a bid for statehood through international bodies.

But the announcement the secretary of state was postponing a visit to the Middle East planned for this week to focus on talks about Syria in Washington raised a few eyebrows about where his "quiet strategy", as he calls it, is actually going.

"Certainly, I do not get the impression that there is much movement on this. It has been quiet diplomacy, so is there something going on behind the scenes we are not aware of? I doubt it very frankly," said expert Marina Ottaway.

"If you extrapolate from past experience, failure is more likely than success," the senior scholar at the Wilson Center told AFP.

"I don't see anything in the situation now that makes it particularly favorable to reaching an agreement that has been elusive for so long."

State Department officials insist their boss remains fully engaged in his efforts, and say he plans to reschedule his trip as soon as possible.

But even the globe-trotting Kerry has warned he is not prepared to make endless futile trips, admonishing both Netanyahu and Palestinian president Mahmud Abbas to make the "tough decisions" needed to restart talks frozen since 2010.

A former US ambassador to Egypt and Israel, Daniel Kurtzer, says the few insights Kerry has given into his strategy make for a "compelling process" which has "gotten them focused."

Kerry has insisted the United States will guarantee Israel's security; coaxed Arab League ministers into agreeing to the principle of land-swaps; and even unveiled a plan to attract $4 billion in sorely needed private-sector investment to the West Bank to help the ailing Palestinian economy.

What the top US diplomat has revealed so far "makes it difficult for any of the parties to simply walk away because there's something in it for them," Kurtzer said.

But Kerry has not talked publicly about his ideas on final status issues, such as the future of Jerusalem demanded by both sides as the capital of their state, the question of the right of return of Palestinian refugees and the outlines of the future borders.

Talks need to resume first. All the rest will follow, he insists.

Neither side wants to be left holding what former US secretary of state James Baker once called "the dead cat" of prospective blame, said former state department top advisor Aaron David Miller.

"Kerry may be able to convince Israelis and Palestinians that neither wants Washington to leave this issue on their doorstep. But getting talks started isn't the same as sustaining them. Another collapse could well leave the peace process not just dead, but dead and buried," Miller warned, writing in Foreign Policy magazine.

The top US diplomat has hammered home the same point, telling an American Jewish forum last week: "We are running out of time. We're running out of possibilities... If we do not succeed now, we may not get another chance."

But Ottaway dismissed such talk as not providing any incentive to stir either side saying "we have cried wolf too many times."

In reality, she insisted, Israel doesn't feel under any particular pressure to come back to the table. Instead, the Jewish state has become quite "relaxed" about the status quo, despite the very real danger of a serious confrontation between settlers and Palestinians on the West Bank.

"There is no intifada, there is no active, dangerous resistance in the territories. They don't feel particularly threatened and they are not in a hurry then to face the difficult problems they know they have to face," she said.

Yousef Munayyer, director of the Palestine Center, agreed writing in an opinion piece for the Jerusalem Fund Tuesday that the US needed to end what he call its "pro-Israel favoritism in return for an even-handed approach."

"Israel is happy to support the negotiations so long as it knows it never has to end the occupation," Munayyer wrote.