FILE - In this Sept. 4, 2008 file photo, Republican presidential candidate John McCain makes his acceptance speech during the Republican National Convention in St. Paul, Minn. Mitt Romney did not mention the war in Afghanistan, where 79,000 US troops are fighting, in his speech accepting the Republican presidential nomination on Thursday. The last time a Republican presidential nominee did not address war was 1952, when Dwight Eisenhower spoke generally about American power and spreading freedom around the world but did not explicitly mention armed conflict. Below are examples of how other Republican nominees have addressed the issue over the years, both in peacetime and in war. (AP Photo/Jae C. Hong, File)

Sen. John McCain (R-Ariz.) continued his harsh criticism of the Supreme Court's Citizens United ruling this week, calling it the bench's "worst decision ever."

“They said money is free speech. Since when is money free speech?” McCain asked a crowd at an event put on by the Oxford Union at the University of Oxford, according to the Oxonian Globalist. “Money is money.”

The Supreme Court's 2010 ruling, which allowed corporations, unions and individuals to pour unlimited amounts of money into elections through super PACs, has elicited strong responses from McCain in the past. Earlier this year he predicted that the unfettered influx of money, often from undisclosed sources, would lead to "huge scandals" in upcoming elections.

McCain has traditionally been one of Congress' most enthusiastic supporters of campaign finance reform, and he lamented the demise of such efforts in the wake of the Citizens United decision. At times, he's appeared to act as if he's willing to accept defeat.

Congressional Democrats have since pushed the DISCLOSE Act, a response to Citizens United that sought to rein in the flow of secret and foreign money into elections. McCain first refused to support it in 2010 over his belief that it disproportionately favored unions. Democrats proposed another version of the bill this year, but McCain again demurred over the same concerns, despite guarantees that it treated corporations and unions fairly.