Even in a political season marked by unprecedented levels of political spending, Sheldon Adelson stands alone.
In recent days, Mr. Adelson, a billionaire casino owner, and his wife, Dr. Miriam Adelson, gave $10 million to Restore Our Future, a “super PAC” backing Mitt Romney, people with knowledge of the contribution said Wednesday. The move leaves the Adelsons by far the most prolific campaign donors in the country.
All told, they have given at least $35 million to pro-Republican super PACs during the 2012 campaign, along with several hundred thousand dollars’ worth of $2,500 checks directly to federal candidates. That is more than twice as much money as the closest competitors for the title, the conservative Texas billionaire Harold C. Simmons and his wife, Annette, making Mr. Adelson a uniquely powerful force in the annals of presidential politics.
In the wake of court rulings and other actions that have largely deregulated the campaign finance system, wealthy donors and corporations are planning to pour hundreds of millions of dollars into this year’s presidential and Congressional elections, mostly in support of Republicans.
The cascade of money has left President Obama struggling to keep up, with few Democrats willing to write multimillion-dollar checks to super PACs, in part because many of them object to the existence of super PACs in the first place.
It has also set off an arms race among Republican candidates for the allegiance of a small group of very rich donors. With a net worth of roughly $25 billion, Mr. Adelson is among the richest of all: In an interview with Forbes magazine this year, he suggested he would consider personally spending as much as $100 million on the 2012 elections.
Many wealthy donors have put their money into issue advocacy groups that are not required to disclose their identities to the Federal Election Commission, leaving unknown the true scale of outside money flowing into the 2012 campaigns. A group of conservative donors led by Charles and David Koch, for example, have pledged to raise as much as $400 million for issue groups, including the Koch-founded Americans for Prosperity, and Mr. Adelson himself has financed such organizations in past elections.
But during the Republican primaries, Mr. Adelson stood out for his willingness to spend money on super PACs, which must register with the election commission and disclose details of their contributions and spending. The Adelson family almost single-handedly bankrolled Winning Our Future, a super PAC backing Newt Gingrich, a Romney rival, during the primaries, giving the group more than $20 million.
Winning Our Future pounded Mr. Romney with millions of dollars in radio and television advertisements this winter, injecting into the race some of the toughest and most sustained attacks on his record at the private equity firm Bain Capital.
Mr. Adelson has in the past publicly expressed doubts about Mr. Romney, describing him as timid in comparison with Mr. Gingrich.
But although Mr. Romney is barred from specifically asking Mr. Adelson to contribute large checks to Restore Our Future for his benefit, he has been courting him since January, around the time the Adelsons began giving millions of dollars to Winning Our Future for Mr. Gingrich.
At the time, Mr. Adelson relayed assurances that he would support Mr. Romney’s super PAC even more generously should he become the nominee, saying that he was committed to defeating Mr. Obama.
Mr. Gingrich dropped out in May. Later that month, Mr. Romney and Mr. Adelson met for lunch at Mr. Adelson’s Las Vegas hotel, the Venetian. By last week, according to Politico, Mr. Adelson was considering a contribution of $1 million to $10 million to the pro-Romney super PAC.
Mr. Adelson is close to many of Mr. Romney’s other supporters, particularly wealthy Jewish donors, with whom he has served on the board of the Republican Jewish Coalition.
He is known for his influence in Israeli politics and his hawkish views on American foreign policy, views shared by Mr. Gingrich and to some extent by Mr. Romney. And Mr. Adelson has ties to Restore Our Future; the group’s political director, Carl Forti, helped run Freedom’s Watch, an issue advocacy group to which Mr. Adelson gave $17 million during the 2008 election.
Mr. Forti declined to comment, as did a spokesman for Mr. Adelson.
Some of the leading Republican super PACs were established during the 2010 elections, raising tens of millions of dollars to counter labor unions and helping Republicans to win control of the House.
Democrats have since sought to match Republicans’ super PAC advantage, but with little success. The Adelsons’ $35 million is more than the three leading Democratic super PACs have raised combined. The top donor to Democratic super PACs is Jeffrey Katzenberg, the studio executive, according to the Center for Responsive Politics. He had given just over $2 million through the end of April.
“For the conservatives backing Mitt Romney, these multimillion-dollar investments are small pittances compared to the return they will make when their industries are deregulated and their tax cuts even more than President Bush prescribed,” said Bill Burton, a spokesman for Priorities USA, a super PAC backing Mr. Obama. “Right-wing Republicans will literally pay any price to see to it that their candidate Mitt Romney is elected.”