WASHINGTON — There was a time not so long ago when political contributions from Americans supportive of Israel inevitably veered toward those Congressional candidates who were the most hawkish and outspoken in defending Israel and its security.

No longer. While aggressive defenders of Israel still dominate the debate, more moderate voices in the Jewish community — led by J Street, a Washington lobbying group — are expanding their ability to generate money and political capital for pro-Israel candidates who favor a less confrontational approach to the Israeli-Palestinian conflict and other issues.

This week, J Street is expected to land one of its biggest names when it announces its endorsement of Senator Dianne Feinstein, the veteran Democrat from California who is chairwoman of the Senate Intelligence Committee, an important forum for Middle East intelligence. With Ms. Feinstein’s acceptance of J Street’s endorsement, the group’s political action committee plans to raise at least $100,000 for her re-election bid, the officials said.

Founded in 2008, J Street is on pace to set a fund-raising record this election. By November, it expects to raise nearly $2 million for more than 60 Congressional candidates whose views on Israel align with its own, said Alexandra Stanton, a co-chairwoman of the PAC, and she said it had tapped into pro-Israel donors who had no real political outlet before now. Several leaders from J Street, along with other Jewish groups, attended a White House reception with President Obama on Wednesday as part of Jewish Heritage Month.

Jeremy Ben-Ami, president of J Street, said in an interview that “the assumption has always been that to run for office, you have to run to the right on this issue with a relatively hawkish view on Israel and the Middle East — the ‘Israel right or wrong’ position.”

“We’re changing that calculus,” he said. “We are beginning to organize a very, very large network of people in the middle.”

In the past, some Congressional candidates were reluctant to take J Street’s money because of charges from some American Jewish leaders and Israeli officials that the group’s moderate positions — it supports increased diplomacy, a two-state Israeli solution and continued aid to the Palestinian Authority — made it “anti-Israel.”

“These are people who cannot be considered friendly to Israel,” said Morris J. Amitay, a former executive director of the American Israel Public Affairs Committee, widely considered the most powerful American lobbying force on Israeli matters. Aipac has generally supported a more aggressive defense of Israel, including possible use of American military force against Iran.

Josh Block, another former Aipac official, called J Street “a gnat” in the Israel debate and “a fringe organization with no credibility.”

Capitol Hill critics say J Street has been unnecessarily sharp-elbowed in attacking lawmakers over policy differences, leading to friction with onetime supporters like Representative Gary L. Ackerman, Democrat of New York, who broke with the group last year over its support for a United Nations resolution criticizing Israel’s West Bank settlements as illegal.

For J Street defenders, the vitriol is a sign that the group is beginning to have an impact.

Ms. Feinstein is regarded as a strong supporter of Israel — “obviously, we’re going to back up Israel” in any military conflict against Iran, she said in a recent CNN interview — and her acceptance of J Street’s endorsement is seen as buoying the group’s political credentials. Bill Carrick, the senior strategist for the Feinstein campaign, said that the senator agreed with many of J Street’s principles and that the decision to accept the group’s endorsement was simple.

“We didn’t look at it as picking sides in the debate,” he said. “They wanted to endorse her and, basically, she said fine.”

Tammy Duckworth, an Iraq war veteran who is challenging Representative Joe Walsh, Republican of Illinois, a staunch Israel defender, has also aligned herself with J Street. The group’s leaders said its political action committee expected to raise $50,000 or more for her.

“I stand by Israel,” Ms. Duckworth said in a telephone interview, “but from everything I’m hearing, a two-state solution is really the way forward. Sometimes the best security is peace.”

Her moderate stance stands in contrast to that of Mr. Walsh, who wrote in an op-ed piece this month in The Washington Times that a single Israeli state is “the only viable solution for the Middle East,” and suggested that the Palestinians move to Jordan.

So far this year, J Street is endorsing and raising money for more than 60 candidates — all Democrats — including the Senate campaigns of Representatives Martin Heinrich of New Mexico and Tammy Baldwin of Wisconsin and the re-election campaigns of Senator Sherrod Brown of Ohio and Representatives John D. Dingell of Michigan, Keith Ellison of Minnesota, Anna G. Eshoo of California, and Melvin Watt of North Carolina.

Whatever inroads it has made, J Street lags far behind Aipac in terms of both money and influence. The influence gap was on display in March, when Aipac and J Street each held their annual conferences in Washington.

J Street drew a record number of attendees — 2,500 — as well as speeches by Ehud Olmert, the former Israeli prime minister, and other notables. But it could not compete for global news coverage or firepower with Aipac’s conference, which featured policy-defining and fist-pounding speeches defending Israel’s security by President Obama, Mitt Romney and Prime Minister Benjamin Netanyahu of Israel.

American Jews, pro-Israel Christian evangelicals and other advocates for Israel represent a sizable political bloc, raising more than $12 million for candidates in the 2010 election cycle, according to data from the Center for Competitive Politics.

Aipac, unlike J Street, does not have a political action committee and so does not raise money directly for candidates. However, political analysts say the bulk of the money from Israeli-focused groups and individuals comes from harder-line factions aligned with Aipac and like-minded groups.

The biggest donor to emerge during the current campaign is the billionaire casino magnate Sheldon Adelson, a pro-Israel hawk. He made headlines during the Republican presidential primaries when he and his wife gave $10 million to a group supporting Newt Gingrich, who called the Palestinians an “invented people” during the campaign.

While the liberal philanthropist George Soros gives J Street about $500,000 a year, it has no donor near the financial scale of Mr. Adelson.

Still, leaders of J Street and politicians aligned with the group say they believe they have helped shift the debate in Washington, broaden the politically acceptable options in Israel and advance an agenda that they characterize as both “pro-Israel” and “pro-peace.”

J. J. Goldberg, editor at large for The Forward, a Jewish newspaper, and author of “Jewish Power: Inside the American Jewish Establishment,” said he was impressed by the inroads that J Street had made politically and financially.

“I’m stunned that there are so many members of Congress willing to take their money,” Mr. Goldberg said. “The fact that they’ve got 60 candidates who aren’t afraid to accept their ‘pro-Israel, pro-peace’ argument is a real breakthrough.”