Adelson -- Wikipedia puts his worth at more than $24 billion -- has promised to put $100 million into efforts to deny President Obama a second term, The New York Times reported. He is giving heavily to the Republican Jewish Coalition, which plans an advertising campaign titled "My Buyer's Remorse."
The campaign is aimed at voters in three key swing states, Florida, Ohio and Pennsylvania. Florida has about 600,000 Jewish voters, and a swing of a few percentage points towards the likely Republican nominee, Mitt Romney, could deny Obama the state.
In recent decades, Jews have been among the most reliably Democratic voters. A recent Gallup poll showed 67 percent supporting Obama and 25 percent Romney.
If Romney gets one-quarter of the Jewish vote, he would actually be doing better than any recent Republican. But Adelson and his allies hope that anger over Obama's Middle East policy can pull more Jews into Romney's camp, the report said.
Michael Goldstein, a New Jersey community college administrator, told the Times he plans to campaign for Romney after voting for Obama four years ago. He cited Obama's position on Israel and what he perceives as disrespectful treatment of Prime Minister Binyamin Netanyahu -- but he is also disappointed that Obama has failed to push for gun control.
Republicans hope more Jews will head in that direction.
"We don't need to get a majority of the vote to win," said Matt Brooks, the coalition's executive director. "When we take votes away from Democrats, we are taking votes from a key part of their constituency."