Republicans in Congress are touting their replacement bill for Obamacare as a cost-saving alternative, but those who work on behalf of older Americans are convinced it would weaken Medicare and put health insurance out of reach for millions.

The American Health Care Act would allow insurance companies to charge people in their 50s and early 60s five times as much as younger adults for premiums. The current cap is only three times as much. AARP is branding the difference an "age tax," and Lisa Dedden Cooper with AARP Michigan says it would hit the most vulnerable populations the hardest.

"Say you're a 64-year-old, but you are lower income, you're making $15,000 a year. With the changes under this legislation, your premiums would be expected to go up by $8,400 a year."

Republicans point out that the plan does include a tax credit that increases for older adults to help defray costs. But the legislation would also eliminate some other tax credits that have helped expand insurance coverage under the ACA. The American Hospital Association and the American Medical Association are among the groups also opposing the bill.