Benjamin Netanyahu is the thirteenth person to be prime minister of Israel. Barack Obama is the twelfth occupant of the White House since Israel was created in 1948. In the 61 years since then, US presidents and Israeli prime ministers have met dozens of times, sometimes, as in negotiations at Camp David in September 1978 and in July 2000, for days at a time.

Occasionally, Israeli leaders have looked almost as comfortable in the official residence of the US head of state as they were at home.

So there is the quality of a soap opera about the long-awaited visit to Washington by Netanyahu for his trumpeted first meeting with Obama as president. The script is largely written. They will retreat for a chat with carefully-chosen advisers and re-emerge for a joint press conference, probably somewhere nice, like the Rose Garden. It always looks lovely in the photo albums.

There definitely won’t be any surprises. US and Israeli officials talk to each other constantly. There is an amazing amount of interchange of personnel between the governments of Israel and the US.

An example, among many, is Stanley Fischer, now governor of the Central Bank of Israel. He was previously vice-chairman of Citibank, deputy managing director of the IMF, chief economist at the World Bank and, in President Clinton’s first term, a White House adviser.

Obama’s chief of staff Rahm Emmanuel, although he probably dances better than he fights, was a volunteer civilian supporter of the Israeli army in 1991. When it comes to deciding Middle East policy, the rules of engagement between Israel and US are unchanging: no secrets. They probably could not keep them, anyway.

There will not be any significant policy departures either. The only question about the US’ relationship with Israel under Obama is whether it will be very close or inseparable.

And yet there is a quiver of uncertainty in the conjoined Israeli-US backbone this spring which suggests that everything in the White House garden isn’t as rosy as it looks. The first is the personal chemistry between Netanyahu and Obama.

Confrontational reputation

The Israeli prime minister, once a relentlessly combative advocate of constant confrontation with Israel’s opponents, has mellowed (if that is the right word) over the years. The smile, which once invariably had a hint of menace, looks sincere, even heartfelt.

But Netanyahu’s reputation goes before him. When he was previously prime minister in 1996-99, he had many meetings with President Clinton who came to loathe him. The White House spokesman at the time Joe Lockhart has been quoted as describing Netanyahu as “one of the most obnoxious individuals you’re going to come into - just a liar and a cheat. He could open his mouth and you could have no confidence that anything that came out of it was the truth.” If it was not all so serious, you would have to laugh.

Netanyahu on the other hand may find it difficult not to patronise the new, younger and inexperienced president. Some observers fear that Obama’s charm may be counterproductive. Netanyahu, a natural bully, could conclude that he is a pushover.

Nevertheless, there is little doubt who is going to feel more nervous on 18 May. Labour Party leader Ehud Barak, a member of Netanyahu’s coalition, said in April that the Israeli prime minister was going to have stop prevaricating and back the two-state solution. A diversionary attempt to focus attention on Iran, with which the US is seeking to start a dialogue, may irritate rather than distract. Netanyahu’s best tactical position is to agree generally with Obama and express helplessness about the lack of credible Palestinian counterparties.

But Obama, nevertheless, will want some sign that Netanyahu is prepared to back the US’ new Middle East peace strategy which the White House is preparing to unveil.

At its heart is a commitment to the principle of an independent Palestinian state. Securing Netanyahu’s open support for this goal would reassure the US’ Arab allies, although they do not have any option but to go through the motions, that they are not about to be led, yet again, up a blind alley. Failure to do so would only fuel the radical impulses sweeping populous Sunni Muslim Middle East states since the assault on Gaza at the end of 2008. Netanyahu will not want Israel to be held responsible for that.

Of course, he might call the US’ bluff. Other Israeli leaders have in the past and got away with it. But there is in the hope among US voters that Obama will not fail so soon a challenge that Netanyahu cannot ignore. Saying no will be his default position. But the consequences for Israel, the US, Washington’s long-suffering Middle East friends and - above all - Obama’s reputation could spell trouble for everyone.