Wall Street executives and hedge fund managers are so far the most conspicuous donors to "super political action committees," followed by titans of energy. But for raw impact, no one beats casino billionaire Sheldon Adelson, whose extended family has contributed $11 million to a super PAC backing Newt Gingrich.

Recent financial disclosures from super PACs give insight into which people, corporations, and unions are writing big checks in hopes the super PACs can succeed in influencing the 2012 presidential race. Mr. Adelson's contributions, say political analysts, helped Mr. Gingrich to get back in the race after fourth-place showings in Iowa and New Hampshire.

The Adelson-Gingrich connection dates from the candidate’s tenure as US speaker of the House in the late 1990s, when the two men conferred over legislation in support of Israel. Those ties are especially on display in Nevada, which holds its presidential caucuses Saturday.

As of Feb. 2, the Gingrich campaign itself had yet to buy TV, cable, or radio ads in the Las Vegas media market. But the Adelson-funded Winning Our Future super PAC did give Gingrich a radio presence in the run-up to the Nevada caucuses, running 203 pro-Gingrich ads and 62 anti-Mitt Romney ads, according to Media Monitors, based in White Plains, N.Y. The Romney campaign and Restore Our Future, a super PAC backing Romney, otherwise dominated TV, cable, and radio in the Las Vegas market, producing 1,116 spots overall, compared with 277 for Gingrich, 256 for Ron Paul, and seven for Rick Santorum.

Typically, the Nevada caucuses begin at 9 a.m. and end at 3 p.m. But in an 11th-hour decision, the Nevada Republican Party, with support from Mr. Adelson, added a special caucus venue at the Adelson Educational Campus, a private school in Las Vegas, to encourage participation by Orthodox Jews after sundown. This caucus begins at 7 p.m. As a footnote, Gingrich is staying at the Venetian resort, a subsidiary of Adelson’s Las Vegas Sands.

Often viewed as a conservative counterpart of financier George Soros – whose millions helped fund organizations that set out to defeat President Bush in the 2004 campaign – Adelson has been an ATM machine for GOP candidates and party organizations, especially in his home state of Nevada and other states with gambling interests.

Some examples:

• Mr. Adelson has given $361,900 directly to GOP congressional and presidential campaigns since the 2008 campaign cycle, according to the Center for Responsive Politics in Washington.

• From 2000 to 2010, Adelson and his companies donated $5.3 million to state-level Republican candidates, party committees, and causes, according to the National Institute on Money in State Politics.

•He also spent $3.3 million backing conservative advocacy groups in the 2008 campaign cycle, just behind Mr. Soros, at $4.5 million, and Hollywood producer Stephen Bing, who also backs liberal causes, at $3.3 million.

By contrast, Adelson wrote a $2,500 check to the Gingrich presidential campaign back in August, the maximum allowed under campaign-finance law.

Until the US Supreme Court’s 2010 decision Citizens United v. Federal Elections Commission, federal law limited the amount individuals and corporations could contribute to directly advocate for or against a candidate. In this decision, the Supreme Court called such advocacy an expression of political speech that government has no business to regulate, but also provided that Congress could require corporations and individuals to disclose their spending.

“Disclosure permits citizens and shareholders to react to the speech of corporate entities in a proper way,” said Justice Anthony Kennedy, writing for the majority.

So, what are citizens to make of the largest contributions in support of a political candidate in US political history? If Adelson’s funding proves to be a game-changer in Gingrich’s quest for the White House, does the casino operator expect anything in return?