Republican presidential hopeful Mitt Romney waded into the hot-button issue of Medicare, proposing to offer future seniors a choice between the current fee-for-service health plan or a voucher to purchase health insurance plans offered by private insurance companies.

Mitt Romney waves after speaking at the Defending the American Dream Summit, Friday, in Washington. (AP Photo/Haraz N. Ghanbari)

The proposal, offered to conservative activists Friday afternoon, would be similar to one proposed by Republican Rep. Paul Ryan of Wisconsin earlier this year, but with one big difference. Mr. Romney, the former governor of Massachusetts, said he would keep the current system as an option, while Mr. Ryan and House Republicans voted to drop traditional Medicare altogether, except for those now 55 and older.

Still, the overall impact of the Romney and Ryan plans might not be that different over time. Under Mr. Romney’s proposal, if competition from private plans drove down the cost of those options, premiums would rise on the traditional fee-for-service option, coaxing seniors away from the government-run plan, the Romney campaign said…