McCain reassured the audience at a recent debate that the program's financial challenges are less severe than those confronting Medicare, the giant health care program for older Americans.
"We know what the problems are, my friends, and we know what the fixes are. We've got to sit down together across the table. It's been done before," he said in support of his push for a bipartisan commission.
Three years after the collapse of President Bush's plan to overhaul the program, Social Security has played only a modest role in a fall campaign dominated by the economy and punctuated by a decline in the retirement savings of millions.
And with both men shying away from specifics, the exchanges are more rhetorical than substantive.
Obama aired a television ad saying McCain campaigned in favor of Bush's failed 2005 proposal, which it characterized as "cutting benefits in half, risking Social Security on the stock market."
In fact, the allegation about cutting benefits was from a study of Bush's plan showing that under one scenario, the benefits of higher-income retirees could be cut in half from what is promised
- beginning in 2080 - meaning that most of those affected have not yet been born.
Nor has McCain proposed investing the government's payroll tax receipts in the stock market. But he has previously proposed giving workers the option of diverting some of their Social Security taxes into such private investments.
"I do not and will not privatize Social Security," McCain says. "It's not true when I'm accused of that."
Polling over the years has shown the word "privatization" evokes hostility among voters.
McCain's denials are hard to square with his previous comments. "Without privatization, I don't see how you can possibly over time make sure that young Americans are able to receive Social Security benefits," he said in November 2004. He also supported Bush's 2005 plan, which envisioned smaller than-promised benefits for future retirees and the option for workers to privately invest a portion of their payroll taxes to provide a supplement to the government benefits.
No matter the politics, there is no dispute that the venerable retirement security program will need a fix. Currently, 34 million retirees and their dependents receive monthly benefit checks, as do 6 million survivors of deceased workers and 9 million disabled workers and their dependents.
Government experts project the Social Security trust funds will begin paying out more than they collect in payroll taxes in 2017, and be exhausted in 2041. At that point, benefits would fall to 78 percent of promised levels.
Over the next 75 years, the program's most recent annual report projected the trust funds "would require additional revenue equivalent to $4.3 trillion in today's dollars to pay all scheduled benefits."