Now AIPAC, the most prominent pro-Israel lobby in the U.S., is rapidly losing ground in its biggest test as it mounts an all-out campaign to kill President Barack Obama's nuclear deal with Iran.
The effort to stop the Iran agreement pits it not only against the president but also a swath of the American Jewish community. While AIPAC is on the same side as Israel's Prime Minister Benjamin Netanyahu and Republicans who are taking on the Democratic president, American Jews voted more than 2-to-1 for Obama over Mitt Romney in 2012.
This debate "is treacherous because it exposes too much of the leadership of the Jewish community as being out of step" with the majority of Jews, Robert Wexler, a Jewish former Democratic congressman from Florida, said in an interview.
AIPAC's effort looks increasingly likely to come up short. Republicans in the Senate are united in opposing the Iran deal, but they've been joined so far by only two Democrats, Chuck Schumer of New York and Bob Menendez of New Jersey.
Meanwhile, the White House is closing in on the Democratic votes needed to uphold Obama's promised veto of a resolution rejecting the deal. On Thursday, Democratic Sen. Claire McCaskill endorsed the agreement. Also Thursday, two national Jewish organizations said Obama will address their members by webcast on Aug. 28.
Defeat could have lingering consequences for AIPAC, which boasts a long-successful role advocating for Israel across Congress's partisan divide.
Divisions over the Iran deal are causing "great angst" within the Jewish community, Michael Siegal, chair of the board of trustees of the Jewish Federations of North America, said in an interview.
"If the president prevails, which I believe he will, it means AIPAC will not prevail, and that's not a positive thing for the Jewish community," said Wexler, now president of the S. Daniel Abraham Center for Middle East Peace in Washington. "Even though I support the deal, I want AIPAC to be highly effective."
An AIPAC-backed group, Citizens For a Nuclear Free Iran, has purchased more than 15,000 TV spots in 34 local markets and on national cable for an estimated $9 million to promote its view that the Iran accord threatens both U.S. and Israeli security.
In an email to supporters, AIPAC President Robert Cohen called the group's lobbying campaign "appropriate, legitimate and measured" in its effort "to shape the national debate and impact the congressional response to this bad deal."
AIPAC spokesman Marshall Wittmann said in an email Thursday that its "principled position is supported by a growing bipartisan majority in Congress and by major Jewish organizations throughout the country."
It's not often that AIPAC takes on the president of the United States so directly, but it brings considerable muscle to the fight. It says it has 100,000 members, a paid staff of about 400 and 17 regional and satellite offices that work with local activists and supportive groups.
The group had revenue of about $70 million from contributions and grants in the year ended September 30, 2013, according to its most recent available tax filing. J Street -- its more liberal rival, which supports the Iran accord -- reported contributions and grants of $6.7 million in 2013 and has fewer than 60 employees.
In 2014, AIPAC spent $3 million on Washington lobbying, dwarfing the $400,000 reported by J Street. As the U.S. and five other nations closed in on the agreement with Iran, AIPAC spent $1.7 million lobbying Congress in the first half of this year, according to the nonpartisan Center for Responsive Politics.
AIPAC isn't a political action committee, leaving it to its members to use other channels for contributions to candidates. The Center for Responsive Politics reported that pro-Israel campaign contributions totaled about $12 million in the 2014 election cycle, with a 57-43 percent split favoring Democrats over Republicans. Those figures don't reflect super-PAC contributions, such as casino mogul Sheldon Adelson's $93 million to Republican super-PACs in 2012.
The AIPAC-backed Citizens for a Nuclear Free Iran has said it will spend $20 million on national advertising -- four times what J Street raised for its pro-deal campaign.
The "no" lobby aligned with AIPAC includes groups that have received financial support in the past from billionaire Jewish Republicans such as Las Vegas Sands Corp. founder Adelson, hedge fund managers Paul Singer and Seth Klarman and Home Depot co-founder Bernard Marcus.
Despite its clout, AIPAC has lost other battles with American presidents, including Gerald Ford, Jimmy Carter and Ronald Reagan over arms sales to Saudi Arabia. In one of its biggest setbacks, Reagan prevailed in the early 1980s in selling five AWACs surveillance aircraft to the Saudis, part of an $8.4 billion deal.
A decade later, President George H.W. Bush defied AIPAC by holding up $10 billion in loan guarantees for Israel in a dispute over settlement construction.
As Israel's government has moved to the right in recent decades, splits have opened among U.S. Jews, including on the Iran deal. Even a former executive director of AIPAC, Tom Dine, has endorsed the agreement.
J Street says most American Jews back the Iran accord, while "opponents like AIPAC are spending tens of millions of dollars" to try to turn Congress against "Obama's historic success."
In Twitter messages urging calls to lawmakers, the group says: "Don't let AIPAC speak for you."
AIPAC's leaders respond that they're far from alone, citing opposition to the Iran deal from the American Jewish Committee, the Anti-Defamation League, B'nai B'rith International, and the Jewish federations in cities including Chicago, Cleveland, Detroit, Houston and Miami.
Further, the Orthodox segment of the community "is overwhelmingly against the deal," Nathan Diament, executive director of the Orthodox Union Advocacy Center, the lobbying arm of the Orthodox Union, said in an interview.
Polling conducted last month for the independent Los Angeles Jewish Journal found American Jews split 49 percent for the accord to 31 percent against, with a margin of error of plus or minus 6 percentage points. The poll was conducted shortly after the deal was announced in mid-July but before it had received the scrutiny and debate that has since developed.
Nationally, Americans say Congress should reject the Iran deal by a margin of 56 percent to 41 percent, according to a CNN/ORC poll released Thursday, with a margin of error of plus or minus 4.5 percentage points. The poll, though, shows the deep partisan split on the issue, with Democrats supporting the deal 70 percent to 28 percent with a margin of 8.5 percentage points.
Jews identify themselves as Democrats by more than three- to-one over Republicans, according to a 2013 study by the Pew Research Center. Major organizations such as AIPAC attract members who are more affluent, more Republican and less liberal than the broader Jewish population, according to studies by Steven M. Cohen, a research professor of Jewish social policy at the Hebrew Union College in New York.
Liberal Jewish groups such as J Street are highlighting support from religious leaders and veterans of Israel's security establishment and working with faith-based and peace groups.
Greg Rosenbaum, chair of the National Jewish Democratic Council, said in an interview that he's worried about the potentially corrosive effect of the debate among American Jews.
"I'm trying to tamp down the vitriol so it doesn't look like the Jewish community is engaged in a civil war," he said.
_ Tim Higgins contributed from San Francisco.
