Former Republican presidential nominee John McCain says he's "worried" that billionaire Sheldon Adelson, who reportedly may contribute up to $100 million in support of GOP hopeful Mitt Romney, and others could have an undue influence on elections as a result of the Supreme Court's Citizens United decision.

"I'm not only worried about him, I'm worried about many others," McCain told NBC's David Gregory on Sunday. "I've always been concerned about the labor unions who take money from their union members and without their permission, contribute to causes that they may not support. So am I concerned about the incredible amount of money that's washing around? Yeah."

"Sheldon Adelson makes money from a foreign casino as well," Gregory noted. "You said this week it's tantamount to foreign money getting into the [Romney] campaign."

"I think there will be scandals associated with the worst decision of the United States Supreme Court in the 21st century," McCain explained. "Uninformed, arrogant, naive. I just wish one of [the justices] had run for county sheriff. That's why we miss people like [former Chief Justice] William Rehnquist and [former Justice] Sandra Day O'Connor, who had some experience with congressional and other races."

"Do you think Adelson himself will have undue influence on Mitt Romney?" Gregory pressed.

"Not any more than other people who give lots of money," McCain replied. "The whole system is broken and it's a wash. I don't pick out Mr. Adelson and more than I pick out [AFL-CIO President Richard] Trumka."

"So the fact is that the system is broken. I predict to you that there will be scandals and I predict to you that there will be reform again."

In a Friday interview on PBS, McCain said that Adelson's contributions to Romney's presidential ambitions amounted to "foreign money" influencing a U.S. political campaign.

That remark seemed to be somewhat at odds with Romney's assertion at the Iowa State Fair last year that "corporations are people, my friend."

"I think that in that context he was talking about they are made up of people and that’s true in that context," McCain explained. "But to be corporations for purposes of involving campaigns, to be treated the same as people, I just don’t agree with that."

Watch this video from NBC's Meet the Press, broadcast June 17, 2012.

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