Associated Press
Republican presidential candidate, former Massachusetts Gov. Mitt Romney shakes hands after delivering a speech during the Business Roundtable quarterly meeting at the Newseum in Washington, Wednesday, June 13, 2012 in Washington.

Multiple sources have confirmed that casino magnate Sheldon Adelson is donating $10 million to the Restore Our Future super PAC that indirectly supports Mitt Romney's presidential campaign.

"The $10 million figure appears to be the largest single donation towards Mr. Romney’s efforts so far," the Wall Street Journal reported. "The independent political action committee, by law, cannot coordinate its work with the formal Romney campaign. … Mr. Adelson and his family gave $21 million in total to a PAC supporting (Newt) Gingrich during the early primaries, but turned off the spigot after Mr. Gingrich fell far behind in the races and the delegate count."

The chairman and CEO of Las Vegas Sands Corp., Adelson is worth an estimated $24.9 billion. After a recent one-on-one interview with Adelson, writer Steven Bertoni described the billionaire as "an Israel hawk who has donated hundreds of millions of dollars to Jewish causes" and "had been willing to donate as much as $100 million to his initial presidential preference, Newt Gingrich." (Bertoni also added this nugget: "the $10 million donation he just made to Romney is equivalent to $40 for an American family with a net worth of $100,000.")

"Adelson's help is among the most coveted this cycle," Politico's Maggie Haberman wrote. "The $10 million to Romney is a lot — and he made clear to the nominee … that he would be his biggest super PAC donor — but it's less than he gave Gingrich, with whom he has a personal relationship."

Adelson is far from the first billionaire to donate to Restore Our Future. On Wednesday's Clare O'Connor detailed, "With (Adelson's) gift, the tally of America’s (billionaires) donating to Mitt Romney-backing super PAC Restore Our Future is 32 — or, 8 percent of the Forbes 400."

Even though Adelson had been supporting Gingrich throughout the early phases of the 2012 presidential race, Romney has consistently cultivated a cordial relationship with the pro-Israel billionaire. For example, last year Romney spoke to a Republican Jewish Coalition event that Adelson hosted.

Time Magazine reported about that 2011 visit to see Jewish leaders in Las Vegas: "Mitt Romney, a Mormon who doesn’t gamble, (paid) homage to Adelson this weekend by appearing at his hotel, the Venetian in Las Vegas, for the Republican Jewish Coalition, a group for which Adelson holds a seat on the board of directors."