Several prominent American Jews have formed a new pro-Israel lobby as an alternative to traditional organizations that, they assert, often impede progress in the Middle East because of their generally reflexive support of Israel.

Officials of the new group, called J Street, say they believe the best way to bring security and peace to Israel is to help political candidates who support that country but will occasionally question some of its policies like maintaining or expanding settlements in disputed territories.

For many who follow the intense and complex world of lobbying on Middle East issues in Washington, there is little doubt as to the role J Street hopes to play in American politics — upsetting or at least diluting the influence of groups like the American Israel Public Affairs Committee, or Aipac, the formidable lobby that has long been the dominant voice of American Jewry with regard to United States policy in the Middle East.

“They’re trying to be the un-Aipac,” said Shmuel Rosner, who follows the issue closely as the chief United States correspondent for the Israeli newspaper Haaretz.

The executive director of the new venture, Jeremy Ben-Ami, said in an interview that “a large number of American Jews and their friends have dropped out of the discussion about how to bring peace to Israel and its neighbors because they don’t have a home politically.” He argued that there was a need for an alternative to the traditional groups who say, “to oppose any Israeli policy is to be anti-Israel.”

The new group’s name is a multiple play on words. Not only does the letter “J” suggest a Jewish cause, but “K Street” has come to be shorthand for the Washington lobby industry because many lobbyists’ offices are there. Although downtown Washington’s streets are named for letters in the alphabet, it is also a quirk that there is no J Street to be found between I and K.

The group’s founders say they will provide something else that does not exist: financial support from American Jews for political candidates whose views are not in line with Aipac’s. J Street has established its own political action committee to donate to candidates on the basis of their views about Middle East policy.

So far, according to the most recent quarterly statement filed at the Federal Election Commission, the group has brought in only a handful of contributions, ranging from $250 to $5,000.

Aipac does not have a political action committee and does not donate to candidates but exercises significant influence in other ways. Its prominent members donate heavily as individuals to candidates, and it mobilizes influential supporters in lawmakers’ home districts.

Mr. Ben-Ami, a former domestic policy adviser in the Clinton administration, said his group intended to select a handful of Congressional candidates to support this fall with donations of about $50,000 each.

He said they would choose candidates in June who are willing, for example, to express forcefully their support for a two-state solution to the Israel-Palestine issue and for aid to the Palestinian Authority.

One race that has the potential to provide such a demonstration is the Senate campaign in Minnesota, in which Norm Coleman, the incumbent Republican who is a staunch Israel supporter, is likely to be opposed by Al Franken, a Democrat who might take some positions more in line with those of J Street.

Underlying the formation of the group is a fundamental question that has long vexed the American Jewish community: What is the most effective way to support Israel? Many people involved in Aipac have long argued that American Jews have limited standing to criticize Israel’s policies because they are not themselves facing difficult questions of safety and survival.

Aipac would not comment on the formation of J Street. But some people involved in Aipac noted with satisfaction the vast difference in the size of the two groups: J Street is planning for an operating budget of about $1.5 million, compared with Aipac’s $100 million endowment, membership of more than 100,000 and annual lobbying expenditures of about $1 million.

Victor A. Kovner, a prominent New York lawyer and former corporation counsel for the city who is one of the principal fund-raisers for J Street, said the group’s aim was to undo the notion that “Aipac speaks for American Jews on issues affecting Israel and Middle East.”

He said candidates would also be able to use the group’s endorsements as a shield against accusations that they were anti-Israel. The group’s principal fund-raisers are Mr. Kovner, who supports Senator Hillary Rodham Clinton’s presidential campaign, and Alan Solomont, who supports Senator Barack Obama’s candidacy.

A principal theorist behind the group, J Street officials said, is Daniel Levy, the son of Lord Levy of Britain, who was the Labor Party’s main fund-raiser under Prime Minister Tony Blair.

So far, J Street has raised about $750,000 for its lobbying arm. It is organized as a nonprofit and is not obliged to detail its donations, although Mr. Ben-Ami said that a few people, whom he would not name, had each given gifts of $100,000.