Bernie Madoff's punim may be the best selling mask this Halloween season, but what scares the stuffing out of many Jewish leaders is the new pro-Israel peace lobby called J Street. What has them quaking in their Guccis is the fear that its message appears to be igniting interest in the community and on Capitol Hill despite a frantic campaign to douse it.

The 18-month-old group just held its first national convention in the wake of a massive operation by its hysterical foes to frighten away participants, particularly politicians who might lend it credence. But it backfired. They wound up dramatically elevating the peace lobby's prominence and influence and were responsible for swelling the meeting's attendance and media coverage far beyond the group's wildest dreams. It took AIPAC many years to reach the level J Street achieved in its first outing.

The group comes out of this week as the recognized voice of the pro-peace, pro-Israel Jewish community at the expense of long-standing groups like Americans for Peace Now and Israel Policy Forum. What sets it apart, and so terrifies the hard-line establishment, is that unlike the others it has a political action committee (PAC) that raises and contributes money for political campaigns - something essential to being an effective player today. What's more, it is beefing up its lobbying activities with some respected veteran political operatives.

BUT ITS greatest appeal - and what sends some in the Jewish establishment into paroxysms of fear and panic - is to younger and progressive Americans, particularly Jews, who are turned off by the Israel-first establishment's intolerance of dissent and its steady rightward tilt, something that has been on display in the failed effort to stifle J Street.

And J Street has a sympathetic ear at the White House, which is not unaware of how the old-line organizations worked against President Barack Obama's election while 78 percent of Jewish voters were giving him their support.

The Netanyahu government and its ambassador here may be shunning J Street, but not the White House. The group has been invited to meetings Obama has held with national Jewish leaders, and some of its leaders have close ties to senior policy makers.

I suspect for some, attacking J Street is a backdoor way to attack Obama without doing so openly and risking White House access.

Many also fear that J Street will give the Obama administration political cover in the Jewish community to pressure Israel to adopt peace policies the right doesn't want.

What is it about Obama's talk of peace that terrifies them? After all, George W. Bush, who they profess to admire, also advocated two states and called for a settlement freeze. Could it be that they're worried that Obama, unlike Bush, means what he says?

The epithets hurled by some Jews at J Street - Stalinists, a fifth column, surrender lobby, terrorist sympathizers, toy Jews, pro-terrorist, illegitimate, treasonous, odious, rot - sound like what the Iranians are saying about Israel these days.

With a $3 million budget it certainly is no threat to the money-making juggernaut that is AIPAC, which raises $70 million a year for itself and heavily influences millions more going directly to politicians.

So terrified of J Street were some old-line organizations that they mounted a campaign of calls, e-mails and threats from supporters to politicians to shun J Street lest their political contributions dry up and their pro-Israel bona fides be brought into question. Only a handful buckled. The warnings were delivered privately, usually through individual backers, to give the organizers an insulating layer of what the Nixonites liked to call plausible deniability.

What the panic on the right has done is unintentionally create a new atmosphere for discussing Middle East policy and offer members of Congress a progressive alternative voice to what's been called the status quo lobby.

I HAVE concerns about J Street's rhetoric and some positions, particularly on the Gaza war, Hamas and Iran sanctions, and some of its coalition partners, but dissent and debate in the pro-Israel community is no threat to the survival of the Jewish state. After all, if Israelis can do it, why can't we? I don't care for some of the people who have endorsed the group, but then I feel the same way about some of the backers of AIPAC, ZOA and the others. J Street may not be the "moderate, mainstream" group it claims, but neither is it the extremist, left-wing anti-Israel threat its critics would have us believe.

Notwithstanding all the attention, J Street is no threat to AIPAC, at least not yet. And serious US pressure on Israel is unlikely until the Arabs can make a convincing case that they are ready for serious compromise themselves. So long as Hamas and Fatah are battling to see who defines the future course of the Palestinian movement - secular nationalism or Islamic republic - little can happen.

What is going on is an attempt by the establishment to define what it means to be pro-Israel, to make that definition ever more ideologically restrictive and to paint J Street as unacceptable. That won't work.

Lately we've be subjected to zealots who made aliya and attack dissenters in the Diaspora as unqualified to render opinions that challenge their own narrow-minded views. One even suggested excommunication and wants a global Jewish solidarity conference called to "exorcise the renegades from our midst." Sort of a Jewish version of the McCarthy-era House Un-American Activities Committee; the past six Israeli prime ministers might wind up being excommunicated.

Then there's my former AIPAC colleague Lenny Ben-David (nee Davis), who indicts J Street as anti-Israel because some Arab-Americans who believe in the two-state solution have contributed money to it. That's like calling AIPAC anti-Semitic because it gets money from some Evangelicals who long for a fiery Armageddon for the Jews and Israel.

Hypocrisy and political turf protecting, not concern for Israel, are what's driving the over-the-top J Street opposition.