Democratic presidential candidate Bernie Sanders on Tuesday warned that the country “is going to slip into an oligarchic form of society where a handful of billionaires control our political and economic life” after GOP megadonor Sheldon Adelson announced his support of Donald Trump for president.

During a campaign in Carson, California Tuesday night, which turned into a victory speech after winning the Oregon primary, Sanders said there’s something “even crazier” than the Koch brothers contributing $40 million to maintain the Republican majority in the U.S. Senate. “A guy named Sheldon Adelson—also one of the wealthiest people in America—a billionaire who is prepared to contribute huge sums of money to another billionaire named Donald Trump,” Sanders told the crowd, who booed in return.

“The American people are sick and tired of billionaires running our economy and our political life,” he added.

Adelson formally announced his endorsement of  the presumptive Republican nominee last Friday and urged Republicans to follow suit. “If Republicans do not come together in support of Trump, [President Barack] Obama will essentially be granted something the Constitution does not allow — a third term in the name of Hillary Clinton,” he wrote in an Op-Ed published by The Washington Post. “I’ve spent time talking to Donald Trump. Do I agree with him on every issue? No. But it’s unlikely that any American agrees with his or her preferred candidate on every issue.”

The New York Times later reported that Adelson told Trump in a private meeting last week that he was willing to contribute more than $100 million to help elect him in the fall. During the meeting, Trump reportedly assured Sheldon and his wife Miriam Adelson that he was dedicated to protecting Israel’s security.

This is not the first time Sanders has mentioned Adelson by name. Last December, while campaigning in Nevada, Sanders suggested that the Vegas casino mogul was, in reality, the first-in-the-nation primary of the 2016 election season.

“Many people think the first caucus of the presidential election is held in Iowa. That is wrong. The first caucus was, actually, held many months ago right here in Nevada. It was called the Sheldon Adelson caucus,” Sanders said. “One guy, who’s worth billions, invites Republican candidates and asks: ‘What are you going to do for me?’ And if they tell him the right thing, he will provide them millions of dollars into their campaign chests. That is not democracy. That’s called oligarchy.”