While many think of Medicare as something only older people need to worry about, its advocates say the program is a fundamental promise to all Americans, and they're calling on Congress and the president to keep it.

Lisa Dedden-Cooper with AARP Michigan says a new voucher plan that's being discussed to replace the current Medicare system would have a negative affect on both current and future retirees. AARP's analysis shows a voucher system would dramatically increase health-care costs and make them unaffordable for many on fixed incomes.

Right now, two-million Michigan residents are enrolled in Medicare, with the numbers going up every day. Dedden-Cooper says it's important to remember the program isn't a handout, noting a retiree with an annual income of less than $25,000 dollars already spends one out of every six dollars on health care.

"Beneficiaries are still responsible for paying monthly premiums and co-payments and annual deductibles, on top of what they've already paid into the system through their paychecks over the years."

She says if saving money is the goal, there are other ways to accomplish that, including a proposal that would allow Medicare to negotiate prescription drug prices. AARP has posted information online at AARP.org/protectmedicare.