Sheldon Adelson, the billionaire casino magnate who has helped sustain Newt Gingrich's candidacy with millions of dollars in donations, suggested that the long-shot campaign is all but over.

It appears as though he's at the end of his line, because mathematically he can't get anywhere near the numbers and there's unlikely to be a brokered convention, Adelson said in an interview posted on the Jewish Journal's website.

Gingrich has continued to defy calls to drop out of the Republican presidential primary campaign, paring his staff to cut costs and saying he'll focus on unpledged delegates to the party's convention. But Adelson's remarks underscore the long odds facing the former House of Representatives speaker, with his most stalwart ally conceding Gingrich won't be the nominee.

Adelson has been Gingrich's most prominent backer this campaign. He donated $7.7 million to the political action committee that helped launch Gingrich's campaign, and he and his family have given some $16.5 million to the pro-Gingrich Winning Our Future super PAC, a total that accounts for nearly 90 percent of Winning Our Future's total contributions.

Super PACs can raise unlimited amounts of money, and although they are technically prohibited from coordinating with campaigns, Winning Our Future played a crucial role in reviving Gingrich's candidacy by funding an advertising blitz.

Adelson and Gingrich have a history that stretches back to Gingrich's time in Congress. Both men share hawkish positions on Israel, and Gingrich's continued insistence that the Obama administration is neglecting the threat of radical Islam, particularly Sharia law, aligns with Adelson's views.

I'm in favor of Newt Gingrich because I like people who make decisions, Adelson told the Jewish Journal. He's a decision-maker. You don't need to worry about using the word 'Islamofascist' or 'Islamoterrorist' when that's what they are. Not all terrorists are Islamist but all the Islamists are terrorists.

If Adelson cuts off support to Gingrich, it is possible he would direct his largess toward another candidate. When asked about Gingrich's rivals for the Republican nomination, Adelson professed a personal affection for Rick Santorum but said that I don't want him to run my country and said that Mitt Romney is not the bold decision maker like Newt Gingrich is.

But Adelson has said in the past that he prioritizes unseating President Obama over electing Newt Gingrich (he sported an Obama ... Oy vey! button during his interview, referring to an Yiddish expression of dismay), and his associates told the New York Times that Adelson would likely support Romney if he becomes the Republican nominee.