Billionaire casino magnate Sheldon Adelson just donated $10 million to Mitt Romney's Super PAC, and told Forbes he is willing to spend $100 million or more to ensure President Obama is not re-elected.

Adelson is by far the biggest political donor in American politics. Before this latest contribution, he had given more than $26 million to Super PACs in 2012, according to the Center for Responsive Politics. That includes the $21.5 million he gave to Newt Gingrich's Super PAC, which single-handedly kept the former House Speaker's presidential campaign alive. He's also given $1.3 million to state politics over the years.

While the amount Adelson is willing to spend is staggering, $100 million in political contributions would not put a dent in his largesse. His $25 billion net worth makes him the world's fourteenth-richest person, according to Forbes. To Adelson, $100 million is less than one half of one percent of his net worth—spending it would be the equivalent of a family worth $250,000 spending $1,000.

Adelson's wealth comes from his casino empire in Las Vegas and Southeast Asia. His company, The Las Vegas Sands Corp., brought in $9.4 billion in 2011, according to financial filings.

Politically, Adelson's donations have been heavily Republican. His most pressing concerns, perhaps the driving issues behind his political giving, have been the support of Israel and what he called Obama's 'socialist-style economy.'