(CNN) Many Democrats running for the 2020 presidential nomination want to get more people insured by broadening Medicare to cover all Americans.

But if Sen. Bernie Sanders' sweeping "Medicare for All" plan were enacted, it would mean big changes for the more than 60 million people already enrolled in Medicare, the federal health program for the elderly and disabled.

While the Vermont senator argues that his proposal would provide even more benefits for seniors, others, particularly former Vice President Joe Biden, have warned that it would transform the 53-year-old program beyond recognition, despite keeping the name intact.

"Medicare goes away as you know it," Biden said in July at an AARP candidate forum. "All the Medicare you have is gone."

The question is whether that's better or worse for seniors whose coverage would change -- though the likelihood of any Medicare for All-type program being enacted by Congress also depends on whether Democrats win the Senate in 2020.

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