In the battle for the Republican pro-Israel vote, Newt Gingrich lacks Mitt Romney’s broad base of prominent Jewish donors. But he has something potentially more powerful: the support of one of Benjamin Netanyahu’s most significant American backers, and a relationship with the Israeli prime minister himself that stretches back decades.

Billionaire casino mogul Sheldon Adelson, one of the wealthiest men in the world and a major donor to Jewish and conservative causes, is widely known as a Netanyahu stalwart. Less well known are his equally close ties to Gingrich, to whom he has been a major giver in recent years.

Adelson’s faith in Gingrich hasn’t been particularly contagious. High-profile Jewish supporters of Gingrich remain tough to find, even as Gingrich has rocketed into the GOP lead in national polling. Still, the former House speaker’s ties to Adelson, his relationship with Netanyahu and a foreign policy team packed with neoconservatives leave him well situated in the competition for pro-Israel voters.

Neither a spokesman for Adelson nor for the Gingrich campaign responded to repeated requests for comment for this story. But the alliance of Adelson and Gingrich is famous in Jewish Republican circles.

“They have been tremendous fans and supporters of Newt from day one,” Fred Zeidman, a Texas oil executive and prominent Republican Jewish supporter of Romney, said of Adelson and his wife,

Adelson, who ranked eighth in Forbes’s 2011 list of the richest Americans, is chairman and CEO of the Las Vegas Sands Corp., which owns casinos in Las Vegas and Macau, China. He has been a major funder of Taglit-Birthright Israel, which sends young Diaspora Jews on free trips to Israel, and has been among the most significant American supporters of Netanyahu. In 2007 he launched a free right-of-center newspaper in Israel called Israel Hayom.

At the same time, Adelson is among the largest political donors in the United States. Adelson and his wife rank second among individual contributors to federal candidates, parties and political action committees in the current election cycle, according to the Center for Responsive Politics. Adelson has given particularly heavily to Gingrich-associated organizations. Between 2006 and 2010 he donated $7 million to American Solutions for Winning the Future, one of Gingrich’s political groups, according to a database maintained by the Center for Responsive Politics.

American Solutions shut down in July. Around the same time, Gingrich’s campaign nearly came to a halt as staff members in key states resigned en masse. That same month, Tablet magazine suggested that Adelson had become less than full-throated in his support of Gingrich’s presidential run.