(CNN) -- The influx of cash to Mitt Romney's campaign operation from billionaire casino owner Sheldon Adelson doesn't sit well with Sen. John McCain, a Romney supporter and longtime advocate of campaign finance reform.
The Arizona Republican said in an interview Thursday that Adelson, who reportedly dropped $10 million into the pro-Romney super PAC Restore Our Future this week, was indirectly supplying the American campaign with foreign money.
"Much of Mr. Adelson's casino profits that go to him come from this casino in Macau," McCain said in an interview on the PBS "NewsHour."
McCain continued, "Maybe in a roundabout way, foreign money is coming into American political campaigns."
Adelson is the chairman and CEO of the Sands Corporation, which owns three casinos in Macau along with multiple properties in Las Vegas. The Sands Macau opened in 2004, followed by the Venetian Macao in 2007 and the Four Seasons Hotel Macao in 2008.
Macau, an administrative region of the People's Republic of China, is known for attracting tourists from mainland China and other parts of Asia with large Vegas-style casinos, along with hotels and clubs.
McCain said profits from Adelson's Macau casinos were substantial.
"That is a great deal of money. And, again, we need a level playing field and we need to go back to the realization that Teddy Roosevelt had that we have to have a limit on the flow of money, and that corporations are not people," McCain said.
The last line - that corporations are not people - takes a direct swipe at Romney, who McCain endorsed in May and who uttered the line "corporations are people my friend" at the Iowa State Fair in August.
Romney was making the point that profits from corporations benefit the people who work at them, but Democrats and his then-rivals in the GOP took aim, portraying the candidate as out of touch.
Adelson, who previously supported the super PAC backing Newt Gingrich, was reported earlier this week to have donated $10 million to the group backing Romney. That would bring his total donations this election cycle to more than $30 million, an enormous sum but a drop in the bucket for a man whose estimated worth is more than $24 billion