Sept. 6 (Bloomberg) -- Presidential candidates John McCain and Barack Obama made dueling pitches to the nation's elderly, each vowing to bolster Social Security while offering very different approaches.

Even as the candidates assailed one another's Social Security agenda, they issued a joint statement saying that they will appear together on Sept. 11 -- the seventh anniversary of the terrorist attacks on the U.S. -- at Ground Zero, the site in Lower Manhattan where the World Trade Center towers stood before they were struck by hijacked commercial airliners.

``On Thursday, we will put aside politics and come together to renew that unity, to honor the memory of each and every American who died, and to grieve with the families and friends who lost loved ones,'' their statement said. More details are to be released closer to the event.

Also on Saturday, McCain said he would appoint more than a token Democrat to his Cabinet, if he were elected president.

``I don't know how many, but I can tell you, with all due respect to previous administrations, it is not going to be a single, 'well we have a Democrat now,''' McCain said in an interview with CBS's ``Face the Nation,'' to be aired Sunday.

``It's going to be the best people in America, the smartest people in America,'' McCain said, according to excerpts released by CBS.

Social Security Debate

Obama and McCain addressed the AARP's annual ``Life@50+'' conference separately, both by satellite.

Obama, 47, said he would in about a decade lift the cap on Social Security payroll taxes on those making $250,000 a year or more. That tax is now capped at $102,000 in annual income.

McCain has been less specific about how he would extend the program's solvency. He has said he opposes increasing taxes even as he vowed to leave ``all options'' on the table.

McCain also has called for the creation of a bipartisan commission to propose solutions to extend the solvency of the federal retirement program.

Obama criticized McCain's proposal to create personal accounts, which would allow workers to divert a portion of their Social Security payroll tax to privately held accounts. That approach is similar to a plan President George W. Bush touted in 2005, which Congress refused to enact.

Private Accounts

``Privatizing Social Security was a bad idea when George Bush proposed it, and it's a bad idea today,'' Obama said.

``It would take the one rock-solid, guaranteed part of your retirement income and gamble it on the stock market,'' the Illinois senator said. ``That's why I stood with AARP against this plan in the Senate, and that's why I won't stand for it as president.''

Obama said under the current approach, ``most middle-class families pay this tax on every dime they make, while millionaires and billionaires only pay it on a very small percentage of their income.'' Hence, he said, he would lift the ceiling in about ``a decade or more from now.''

In his remarks to AARP, Arizona Senator McCain did not specifically address Obama's Social Security proposals. Rather, he said he would ``change Washington and stop leaving our country's problems for some unluckier generation.''

Democrats and Republicans must ``sit down together and reach across the aisle together and fix this system,'' he said.

`Going Broke'

At one point, McCain, 72, raised his voice and said: ``Social Security is going broke. Social Security is going broke. Hello?!''

He said his proposal for setting up individual investment accounts would be entirely voluntary, giving young workers the option of setting up their own retirement accounts.

``We're not going to privatize Social Security. It is a government function to provide for those who have worked and earned and saved all their lives,'' McCain said.

``Everyday that we delay, the more radical the fix has to be.''

Later in the day, McCain and his running mate, Alaska Governor Sarah Palin, addressed a rally in Colorado Springs, Colorado, and headed to another event in Albuquerque, New Mexico.

At the Colorado Springs event, McCain and Palin both emphasized what is emerging as the overarching theme of their campaign -- reform of government.

``We're going to stop corruption, and it is corruption, and we're going to stop it, and you're going to help me,'' McCain said.

Obama, who has made a pledge to overhaul Washington a key focus of his campaign, contends a McCain-Palin administration would offer a business-as-usual approach.

McCain says he's ``going to tell those lobbyists that their days of running Washington are over,'' Obama told the crowd today in Indiana. ``Is he going to tell all of the folks who are running his campaign, who are the biggest corporate lobbyists in Washington?''

Obama accused Palin of misleading voters by portraying herself as a politician who has disdained the special spending projects sought by some lawmakers, known as earmarks.

``When you've been taking all these earmarks when it's convenient and then suddenly you are the champion anti-earmark person, that's not change,'' Obama said. ``Come on. I mean words mean something. You can't just make something up.''

To contact the reporter on this story: Edwin Chen in Colorado Springs, Colorado at echen32@bloomberg.netKim Chipman in Terre Haute, Indiana, at kchipman@bloomberg.net

Last Updated: September 6, 2008 21:36 EDT