WASHINGTON -- Even in the era of unbridled campaign contributions, Irving Moskowitz's $1 million donation in February to American Crossroads, the Karl Rove-linked super PAC, is eye-catching.

A retired physician who made a fortune purchasing hospitals and running bingo and casino operations in the economically depressed California town of Hawaiian Gardens, Moskowitz is well-known to those who follow the Israel-Palestine conflict. His contributions to far-right Jewish settler groups, questionable archaeological projects and widespread land purchases in East Jerusalem and the West Bank have routinely inflamed the region over the past four decades and, according to many familiar with the conflict, made him a key obstacle to peace in the Middle East.

Now, at age 83, Moskowitz has turned his money on the American political realm in a more prominent fashion than ever before, funding "birther" groups that question the legitimacy of President Barack Obama's U.S. citizenship and others that stoke fears about the president's alleged ties to "radical Islam."

Although he has funded Republican politicians and organizations in the past, his $1 million donation to American Crossroads is his biggest contribution to U.S. electoral politics to date. Moskowitz did not respond to requests for comment from The Huffington Post. American Crossroads told HuffPost that it does not comment on its donors.

Moskowitz's contribution was made possible by the Supreme Court's Citizens United ruling and a subsequent lower court decision that freed corporations, unions and individuals to make unlimited contributions to independent electoral efforts.

And it indicates that supporters of Israel's right to control the West Bank, occupied since the end of the 1967 war, will vigorously oppose President Obama in his campaign for reelection.

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Moskowitz's long-held desire, as he told the Washington Post in the 1980s, has been to "do everything I possibly can to help reclaim Jerusalem for the Jewish people."

Born in New York City in 1928 to Polish immigrants, Moskowitz spent most of his childhood and teenage years in Milwaukee. Coming of age as a Jewish teenager in a largely German immigrant city helped shape his personal Jewish identity, as did the loss of at least 120 family members in the Holocaust, according to speeches and writings by Moskowitz over the years.

After graduating from the University of Wisconsin Medical School, Moskowitz moved to Southern California to launch his career as a doctor. Soon, he started buying up hospitals, which he would flip, beginning as early as 1969, to pay for land purchases in Jerusalem and for donations to settlers in the West Bank and Gaza.

In 2010, President Obama witnessed firsthand Moskowitz's ability to stir up controversy when the administration attempted to keep pressure on Prime Minister Benjamin Netanyahu's government to impose a freeze on settlements in the West Bank and East Jerusalem.

At the time, Moskowitz was planning to demolish the Shepherd Hotel in East Jerusalem, which he had purchased in 1985, to make way for a new apartment complex for settlers. The Israeli government had long resisted his efforts to bulldoze the building, which had been home to the Muslim grand mufti of Jerusalem who supported Hitler during World War II.

But then, just prior to a meeting between Obama and Netanyahu at the White House, the Jerusalem city government approved the destruction of the hotel and construction of the new settlement.

Israel had already been thumbing its nose at the president's call for a settlement freeze by authorizing new settlements throughout the West Bank. The approval of Moskowitz's development prompted harsh statements of rebuke from the White House and Secretary of State Hillary Clinton.

The destruction of the Shepherd Hotel is just the latest in Moskowitz's long history of support for Israeli settlements. Since 2008, his foundations have given more than $15 million to the cause.

Those donations have gone to some of the most controversial settler activists. In 2010, the latest year for which records are available, Moskowitz and his wife's foundation contributed $1.93 million to the Central Fund of Israel, according to Internal Revenue Service records. Money from the fund has gone to support settlements in the West Bank, according to the New York Times -- including to Rabbi Yitzhak Shapira, who wrote a book justifying the killing of Palestinian babies because of "the future danger that will arise if they are allowed to grow into evil people like their parents."

The Moskowitzes gave $2 million in 2010 to Friends of Ir David Inc., a Brooklyn-based nonprofit. The group funnels money to efforts in the historic City of David, located in East Jerusalem, to purchase land and embark on archaeological projects to prove prior Jewish residency in an effort to reclaim land.

In 2010, the Moskowitzes also donated to groups supporting West Bank or near-West Bank settlements in Itamar, Afula, Hebron and Gush Etzion.

Groups pushing for a two-state solution and a peace treaty between Israel and the occupied Palestinian territories consider Moskowitz's contributions a major roadblock to peace.

"The purchases and grants that [Moskowitz has] given to organizations here in Jerusalem, particularly in East Jerusalem, have made it more difficult to implement a future peace agreement in Jerusalem and has therefore made a future peace between Israel and the Palestinians more difficult," says Ori Nir, the spokesman for Americans for Peace Now.

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While Moskowitz's influence in the Middle East is well known, he is not solely focused overseas. He has been making charitable contributions to nonprofits in the U.S. that promote conspiracy theories about President Obama's birthplace and the rising influence of Islam in American society.

According to IRS records, the Irving I. Moskowitz Foundation gave $50,000 in 2010 to the Western Center for Journalism, a nonprofit founded by World Net Daily editor Joseph Farah, a prominent proponent of birther conspiracies. The center's website currently touts the "investigation" into the president's birth certificate by Maricopa County Sheriff Joe Arpaio, calling it "ForgeryGate."

Moskowitz also provided $100,000 to the Center for Security Policy, a nonprofit warning of the imminent danger of radical Islam in America. The center's founder and president is Frank Gaffney, a neoconservative who has publicly questioned whether the president was born in the U.S. and stated that Obama, in his 2008 campaign, was seeking "the Jihadist vote."

The Norwegian Christian conservative terrorist Anders Breivik -- who last year detonated a bomb in downtown Oslo, killing eight, and then massacred 68 more, mostly children and teenagers, on a nearby island -- cited, among others, Gaffney's writings and publications from the Center for Security Policy in his manifesto against the "Islamic colonization of Europe."

Another $20,000 from Moskowitz's foundations went to the Windsor Hills Baptist Church in Oklahoma City. The Southern Poverty Law Center recently listed the church as an anti-gay hate group after the church's pastor testified before the Oklahoma City council that over half of the murders in U.S. cities were committed by gay people. The church is also a strong supporter of the Israeli settler movement and currently has a video on its website arguing why Israel must permanently occupy territory reaching to the Jordan Rift Valley.

The former pastor of the church (and father of the current pastor) runs Yedidim of Israel, a Christian Zionist organization founded to counter the George W. Bush administration's "road map" for peace. The group, which opposes what it calls "land for peace" deals with the "so-called Palestinians," ran a public relations campaign within the evangelical community and in Washington newspapers against then-President Bush's push for a peace agreement.

But Moskowitz's $1 million donation to American Crossroads is his single biggest contribution to U.S. electoral politics by far.

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Most of Moskowitz's money comes from an unlikely source: bingo. In 1988, he took over a bingo night in Hawaiian Gardens, where he owned a hospital. The bingo night was a cash cow for the city, and Moskowitz built it up into one of the biggest bingo operations in the country.

Moskowitz was required by law to run the game, like all bingo operations, as a nonprofit organization. The nonprofit that runs the bingo night is the same Irving I. Moskowitz Foundation that funds the controversial settler groups. Although Moskowitz had been donating to Israeli causes for years, the bingo money pushed his giving to another level, and he soon became one of the biggest benefactors of Israeli settlements, giving millions of dollars each year through his foundation.

The city of Hawaiian Gardens allowed Moskowitz to open a for-profit card game casino, which further contributed to his personal fortune and helped him to fund activities in Israel and the occupied territories.

Those donations have been controversial not just because of the eventual recipients of the funds, but also because of their tax-exempt status. In 2010, The New York Times found that the money contributed to American nonprofits that gave money to the settlements, while providing legally appropriate funds for schools, food, recreation centers and synagogues, "has also paid for more legally questionable commodities: housing as well as guard dogs, bulletproof vests, rifle scopes and vehicles to secure outposts deep in occupied areas."

The American-Arab Anti-Discrimination Committee, a nonprofit that tracks discrimination against Arab Americans in the United States and researches nonprofits funding Israeli settlements, wants to stop Moskowitz and others from giving money to groups in the U.S. that provide money to the settlers. The ADC is pressuring the IRS to revoke the tax-exempt status of these groups.

"Our argument is that a nonprofit should not engage in activities that are in opposition to American policy," says Abed Ayoub, legal director for the ADC. "We want to raise enough doubt to have the IRS have an audit."

American policy under President Obama has been broadly supportive of Israel, with certain reservations -- among them, the construction of settlements in disputed areas -- and Republicans have used those cracks in the U.S.-Israel alliance to attack Obama in the presidential campaign. While some of the most generous super PAC donors have concentrated their efforts on supporting specific GOP candidates, those whose sole interest is making Obama a one-term president have no better place to put their money than American Crossroads.

The group heads a network of independent Republican groups -- essentially, the "shadow Republican Party" -- organized to beat both President Obama and congressional Democrats in the fall.

"The primary mission of the group is going to be to move Obama out of the White House," says Viveca Novak, communications director for the Center for Responsive Politics, a nonprofit that tracks money in politics. "It's also a group with strong ties to the more ferocious Republicans who are very aggressive about their politics."

Those aggressive Republican operatives also happen to be some of the most respected and well connected in the country. Major figures connected to American Crossroads include Karl Rove, former Republican National Committee Chairman Ed Gillespie and former Mississippi Gov. Haley Barbour.

Moskowitz, with his $1 million contribution, appears more than happy to help them.

"Moskowitz is interested in one thing, and that is supporting people who will unquestionably do the bidding of the most extreme elements of the American Jewish and Israeli polity," says Rabbi Haim Dov Beliak, a member of the now-dissolved Coalition for Justice in Hawaiian Gardens and Jerusalem, an organization that opposed Moskowitz's use of bingo and casino operations to fund settlements in Israel.

"Whatever he gives to the Republican Party or this PAC are in service of pouring the most oil on the fire."