Michael Oren, Israel's ambassador to Washington, is by all accounts an urbane and sophisticated man. The author of a highly praised history of the Six-Day War, he was born in New Jersey, has taught at both Yale and Harvard, and certainly understands the US. It's therefore tempting to wonder what he feels in deepest privacy about the fact that what may yet may prove one of the Benjamin Netanyahu government's more far reaching diplomatic snubs, barring a last minute change of heart, is about to be committed in his name.

Mr Oren's refusal to attend the conference next week of a new Jewish organisation few have heard of outside the US and Israel, has not made headlines in the international press. But the conference will be the moment when J Street, a young but growing lobbying group which describes itself as at once "pro-Israel" and "pro-peace" puts itself on the map. Among the US legislators and officials planning to attend – despite strong efforts to persuade some of them not to – will be President Obama's National Security Adviser General James Jones, who will give a keynote address.

So Mr Oren's decision cannot have been taken lightly. It's hard to take seriously the possibility that Mr Oren, who was appointed personally by, and is in frequent contact with, Mr Netanyahu, took the decision on his own. And while Mr Oren may not have been a diplomat for long, he is surely intelligent enough to have wondered if this was the right moment to absent himself from an American Jewish forum, which however new, is important enough to attract the interest of the White House and strongly supports Mr Obama's desire to see the Israel-Palestinian conflict resolved.

It was after all only this week that Mr Netanyahu himself told the Cabinet that it was time to launch a major international rebuttal exercise against the Goldstone report's severe criticisms of Israel's conduct of the winter war in Gaza, and the more than 1,300 Palestinian casualties it caused. Did Mr Netanyahu not tell his ministers that "the most important sphere we need to work in [against Goldstone] is the sphere of public opinion in the democratic world?" To have at least engaged with J Street would seem, if nothing else, to have been an opportunity to do just that.

It may just be, of course, that J Street's own stance on the Goldstone report was a factor. For while criticising its "flawed mandate" and even more vigorously the resolution at the UN Human Rights Council which endorsed the report last week, it has said that the accusations in the report of possible war crimes by Israel are "deeply troubling" and that Israel should set up its own independent inquiry to investigate to them. And even though Netanyahu's deputy, Dan Meridor, has now openly called for such an inquiry, it is not – at least not yet – government policy.

Which brings us to the real reason for Mr Oren's boycott. For J Street, however modestly, challenges those organisations, led above all by the massively well-funded American Israel Public Affairs Committee, which wants – and has hitherto largely enjoyed – a monopoly as the public voice of US Jewry, and see their job as supporting Israeli governments – especially Likud governments – right or wrong.

It has long been questioned how representative AIPAC is of US Jewish opinion, not least of the 78 per cent of electors who voted Obama last year. A 2008 J street poll found that 60 per cent of American Jews opposed further Israeli settlements and that 88 per cent supported a push for peace even if it meant publicly disagreeing with Arabs and Israelis (Indeed 57 per cent supported it even if it means disagreeing only with Israelis.) Needless to say that is not reflected in the heavily neo-conservative stances on the Middle East adopted by AIPAC, ones which through its influence on the US political scene have tended to ensure there is a less open debate on the Israeli Palestinian conflict among US politicians than even in Israel itself.

An anonymous Israel government official was this week quoted as explaining Mr Oren's boycott of J Street by saying that compared with AIPAC, J Street has "done nothing" for Israel. But this in turn raises the question, emphasised rather pointedly by J Street's emergence, of what being "pro-Israel" really means. As Jeremy Ben-Ami, the group's young founder and director put it to the New York Times last month: "We are trying to redefine what it means to be pro-Israel. You don't have to be non-critical......"

After all there is a legitimate argument – one essentially between Zionists – over whether Israel's long-term interests and security are always best served by the choices of the Israeli government of the day, and whether it is the duty of Jews who are also American citizens to remain silent even if they think they are not. Is it necessarily anti-Israel to worry about the devastating loss of Palestinian civilian lives in last winter's war in Gaza? Is it necessarily "anti-Israel" to believe that the relentless growth of settlements may be deeply injurious not only to Palestinians but to Israel's long-term security?

Representativeness, of course, is not the same as power. J Street has a budget of $3m (£1.8m) and AIPAC reportedly one of $70m. When AIPAC earlier this year fired a seemingly innocuous warning shot over a White House clearly bent on reviving a credible peace process, asking President Obama to ensure that America remains a "devoted friend" of Israel and to condition peace talks on an end to violence, its letter attracted 329 signatories in Congress. When J Street wrote its own letter urging active US involvement in the peace process, it got 87.

Neverthless the emergence of J Street is the first development in a long time to challenge the idea that to be a "friend of Israel" – yes even a "devoted" one – does not, as the US President himself put it during his primary campaign, mean signing up to every tenet of Likud policy. J Street certainly has the potential to help a US President who has seriously lost momentum in the Middle East after Mr Netanyahu's humiliating rejection of a total settlement freeze. In the longer-term – though Mr Netanyahu clearly does not agree – it may actually have the potential to help Israel too.

d.macintyre@independent.co.uk