The issue:

Unless Congress acts, the trust funds that support Social Security will run out of money in 2033, according to the trustees who oversee the retirement and disability program. At that point, Social Security would collect only enough tax revenue each year to pay about 75 percent of benefits. That benefit cut wouldn’t sit well with the millions of older Americans who rely on Social Security for most of their income.

Where they stand:

President Barack Obama hasn’t laid out a detailed plan for addressing Social Security. He’s called for bipartisan talks on strengthening the program but he didn’t embrace the plan produced by a bipartisan deficit reduction panel he created in 2010.

Republican challenger Mitt Romney proposes a gradual increase in the retirement age to account for growing life expectancy. For future generations, Romney would slow the growth of benefits “for those with higher incomes.”

Why it matters:

For millions of retired and disabled workers, Social Security is pretty much all they have to live on, even though monthly benefits are barely enough to keep them out of poverty. Monthly payments average $1,237 for retired workers and $1,111 for disabled workers. Most older Americans rely on Social Security for a majority of their income; many rely on it for 90 percent or more, according to the Social Security Administration.

Social Security is already the largest federal program and it’s getting bigger as millions of baby boomers reach retirement. More than 56 million retirees, disabled workers, spouses and children get Social Security benefits. That number that will grow to 91 million by 2035, according to congressional estimates.

Social Security could handle the growing number of beneficiaries if there were more workers paying payroll taxes. But most baby boomers didn’t have as many children as their parents did, leaving relatively fewer workers to pay into the system.

In 1960, there were 4.9 workers for each person getting benefits. Today, there are about 2.8 workers for each beneficiary, and that ratio will drop to 1.9 workers by 2035.

Nevertheless, Social Security is ripe for congressional action in the next year or two, if lawmakers get serious about addressing the nation’s long-term financial problems. Why? Because Social Security is fixable.

Despite the program’s long-term problems, Social Security could be preserved for generations to come with modest but politically difficult changes to benefits or taxes, or a combination of both.

Some options could affect people quickly, such as increasing payroll taxes or reducing annual cost-of-living adjustments for those who already get benefits. Others options, such as gradually raising the retirement age, wouldn’t be felt for years but would affect millions of younger workers.

Fixing Social Security won’t be easy. All the options carry political risks because they have the potential to affect nearly every U.S. family while angering powerful interest groups. Liberal advocates and some Democrats oppose all benefit cuts; conservative activists and some Republicans say tax increases are out of the question.

But Social Security is easier to fix than Medicare or Medicaid, the other two big government benefit programs. Unlike Medicare and Medicaid, policymakers don’t have to figure out how to tame the rising costs of health care to fix Social Security.

Social Security’s problems seem far off. After all, the program has enough money to pay full benefits for 20 more years. But the program’s financial problems get harder to fix with each passing year. The sooner Congress acts, the more subtle the changes can be because they can be phased in slowly.