IN THIS country, we have always believed that a lifetime of hard work and honest living should be rewarded with a secure and dignified retirement -- and Social Security is the cornerstone of that social compact. Last week, as we celebrated its anniversary, we reaffirmed our commitment to ensuring that Social Security is a safety net that today's seniors and future generations of Americans can count on.

Social Security has lifted millions of seniors and their families out of poverty. Without it, nearly 50 percent of seniors would live below the poverty line. In New Hampshire alone, nearly 231,000 seniors depend on their earned Social Security benefit every month to keep them from falling in to poverty.

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The full measure of Social Security's value for its recipients -- as well as for those who look after and love them -- is incalculable. I know because I've heard it firsthand across this country. And that's why as President, I will protect Social Security for today's seniors and future generations.

We all know the system isn't perfect -- but it isn't broken. The underlying system is sound and the actual problem, a projected cash shortfall over the next 75 years, is relatively small and can be readily solved. For starters, that means strengthening the program over the long-term by returning to basic fiscal responsibility, so we're not borrowing billions from the Social Security Trust Fund.

But protecting Social Security also means opposing efforts to privatize Social Security, as I did when President Bush proposed risky private accounts a few years ago. Privatization is wrong. It tears at the very fabric of Social Security -- the idea of mutual responsibility -- by subjecting a secure retirement to the whims of the market. The Bush privatization plan that Sen. McCain now embraces would tell 39,000 New Hampshire residents that they're on their own, putting them at risk of falling into poverty and costing each of them more than $235,000 over their lifetimes. That's not what this country is about.

It means ensuring Social Security's solvency while protecting middle class families from tax increases or benefit cuts, and without raising the retirement age. What I will do is ask those making over $250,000 a year to contribute a little more as part of a bipartisan plan that would be phased in over many years starting a decade or more from now.

Despite what my opponent might say, I do not and will not support uncapping the full payroll tax. My plan is similar to the rate increases floated by one of Sen. McCain's closest advisors -- an idea he has said he could support.

But the fact is, we won't be able to solve this problem and protect Social Security for good until we unite Democrats and Republicans behind these sensible solutions. We can do this because we've done it before.

In 1983, there were problems with Social Security, and President Ronald Reagan and House Speaker Tip O'Neill worked together to forge an effective bipartisan compromise. That sense of civility and shared purpose is notably absent in Washington today.

We need to reclaim the idea that in this country, we're all in it together. That is America's very promise -- and Social Security's very guarantee. And it requires a President who will change the ways of Washington, protect the people's interests, and bring Americans together to meet the great challenges of our time. That is exactly the sort of leadership I intend to offer.

Sen. Barack Obama is the presumptive Democratic nominee for President.