"I don't think there's much that can be done," he told "Face the Nation" moderator Bob Schieffer.
McCain said he was not surprised by Court's decision: "I went over to observe the oral arguments," he said. "It was clear that Justice Roberts, Alito and Scalia, by their very skeptical and even sarcastic comments, were very much opposed to it.
"I think that it was interesting that they have had no experience in the political arena," McCain said. "I was reminded of the story of Lyndon Johnson, when he was vice president, was told about President Kennedy's appointments of all these brilliant people, and he said, 'You know, I wish one of them had run for county sheriff.'"
The Republican senator noted that in prior Court hearing on the issue of campaign financing, Justices Rehnquist and O'Connor had taken a different position. "Both had significant political experience; Justices Roberts, Alito and Scalia have none," he said.
"We are going to see now an inundation of special-interest money into political campaigns," McCain warned. "I think that diminishes the influence of average citizens."
Schieffer asked McCain if he thought the issue of campaign finance reform was "dead."
"Oh, I think so." He predicted a backlash would occur when people see the amounts of unfettered money, from corporations and unions, that will go into political campaigns.
"But in the short term, the Supreme Court has spoken. I respect their decision," he conceded.
Also on the program, Sen. Dick Durbin, D-Ill., invited McCain to work together with him on a new campaign finance bill.
"I would say to John McCain, join me in a public financing effort," he told Schieffer. "I've got the bill in with John Larson of Connecticut. Let's really take the reform on that many states already have started, including the state of Arizona, to make sure that every candidate of modest means has a chance to run and win."
Federal Reserve Chairman Nomination
Also during the interview, McCain said he is leaning against the reconfirmation of Federal Reserve Chairman Ben Bernanke.
"I'm very skeptical about his nomination. I'm worried that if his nomination is turned down, the effect that it might have. But the fact is that Chairman Bernanke was in charge when we hit the iceberg. And his policies were partially responsible for the meltdown that we experienced. I think that he should be held accountable . . . I'm both concerned and leaning against," he said.
Durbin said he plans to vote for reconfirmation, though he "still has unanswered questions."
Asked about President Obama's passed deadline for closing Guantanamo Bay prison, McCain admitted that the president made a "mistake."
"The president's mistake was announcing the closure within a year without having all the policies in place to achieve that," he said. "So Guantanamo Bay must remain open until such time as we have a coherent, comprehensive policy addressing the detainees. And many of them cannot be released, especially to some of the countries that . . . they've been released to, and they've gone back into the fight," he told Schieffer.