Reading the front page of my Hebrew paper last weekend, I tried to imagine an American senator saying something like, "I have great respect for the Israel Defense Forces. But eventually Israel will have to leave the West Bank. In its heart, the Israeli nation has already decided. The Israeli army should not create a rift with Palestinians that haunts us for generations. Think of Palestinians stripped at the checkpoints only because there might be terrorists among them. Think of those who stand for hours at checkpoints because we fear that a booby-trapped car could pass through."

I didn't have to make up that speech from scratch, because I was reading about Ehud Olmert saying words very similar to a forum of IDF commanders in the West Bank. The prime minister could say that despite their short-term security benefits, West Bank checkpoints have long-term moral and strategic costs for Israel. How many pro-Israel members of Congress fear that if they voiced the same concerns, AIPAC would soon be encouraging donations to their next primary opponent?

Such melancholy reflections always lead to the next question: Why are AIPAC and rightist attack groups like CAMERA (the Orwellian-named Committee for Accuracy in Middle East Reporting in America) alone in the U.S. political arena as "advocates" of Israel's interests? Why isn't there a liberal pro-Israel lobby, one that promotes United States involvement in achieving a two-state solution?

As of today, the answer to that question is: There is such a lobby. It's called J Street after the thoroughfare missing from the Washington grid -- much as a liberal Israel lobby has been lacking from Washington. From my perspective, this is a very welcome addition to the political map.

Today's public launch follows many months of organizing led by the new group's executive director, Jeremy Ben-Ami, a media consultant and former Clinton administration staffer. J Street's advisory council includes prominent liberal fundraisers, such as Alan Solomont, former national finance chair of the DNC, and New York attorney Victor Kovner. (Ben-Ami notes that Solomont is now raising cash for Barack Obama, and Kovner for Hillary Clinton.) Among other members are former ambassador to Israel Sam Lewis and David Kimche, ex-director general of the Israeli Foreign Ministry. Unlike existing Jewish peace groups, J Street is registered for tax purposes as a 501(c)(4) organization, meaning that it can operate fully as a lobby. A sister organization, J Street PAC, will endorse and raise money for candidates.

To win J Street PAC's backing, Ben-Ami told me, a candidate's position should be that "the single most important step to support Israeli security and U.S. interests is to reach a negotiated peace agreement, a two-state solution, between the Israelis and Palestinians. The group is looking for politicians who back policies of "engagement and diplomacy" in place of exclusive reliance on military options. Phrased less diplomatically, J Street seeks politicians who advocate a clear shift from the disastrous policies of the Bush years.

As I've written here and at greater length in the UK-based Prospect (no relation), attributing U.S. policy in the Middle East entirely to AIPAC, or a wider and more amorphous "Israel lobby," is a mistake. Historically, America's actions in the Middle East have been bound by its commitment to Israel's survival on the one hand, and by the need to maintain ties with pro-Western Arab states on the other. But within those constraints, AIPAC has sought to keep U.S. policy almost entirely on the side of meeting immediate Israeli security needs, ignoring the strategic interest that both Israel and the United States have in peace between Israel and the Arab states. The veteran lobbying group has taken a zero-sum approach, in which restricting U.S. relations with the Palestinians and other Arab and Muslim actors is automatically -- and falsely -- presumed to be good for Israel. At times, it has supported initiatives that have hampered the Israeli government's own peace efforts. Yet to a large extent, it has managed to equate this agenda with being "pro-Israel."

As a counterweight to AIPAC, J Street has the potential to make several essential contributions. First, it's no secret that there's a strange gap between Israeli political debate and political discussion about Israel in the United States. In Israel, mainstream politicians talk about giving up pieces of East Jerusalem; ex-generals and diplomats urge negotiating peace with Damascus and with Hamas. It's logical to presume that some U.S. senators and representatives, especially liberals, feel boxed in by the terms of debate in Washington. The new lobby's existence could allow them to speak more freely, with the knowledge that they have backing from constituents and donors.

Within the U.S. Jewish community, there's another gap: between the hawkish views expressed by leaders and "pro-Israel" activists and the more dovish opinions of much of the community. The new organization should give dovish Jews an avenue to express their concern for Israel's future, and to escape the sometimes painful dissonance between their progressive domestic concerns and supporting Israel. Once the debate widens, a wider spectrum of Israeli opinion might be heard within the U.S. community, where politicians and intellectuals from the Israeli right have dominated the speaker's dais. J Street intends to base its fundraising largely on the Obama model of small donations gathered online -- a major step toward democratizing the community by balancing the political clout of large donors. While Jewish hawks often express their concern about whether young Jews will identify with Israel, it's actually J Street -- and other, existing dovish groups -- that will ease the dilemma of that constituency: They offer an alternative between the all-or-nothing propaganda of the Israeli right and the equally noxious all-or-nothing agitprop of groups that portray Israel as the sum of all evil.

Most important, of course, J Street could contribute to a shift in American policy toward a win-win-win approach: active, intense U.S. involvement in peacemaking is good for Israel; it is also good for the Palestinians; and it eases American relations with the entire region. Favoring diplomacy over military responses could open the way to peace between Israel and Syria, and even lead to a peaceful resolution of the confrontation with Iran over its nuclear policy.

In the short term, we'll know J Street is succeeding when a senator can merely express the same concerns over what happens at West Bank roadblocks that Ehud Olmert has voiced. In the long term, it might change not only the political map in Washington but the actual map in the Middle East.