It is less clear how young people would respond to the Medicare model or other penalties for delaying enrollment.

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Republicans have refined their "premium support" model of Medicare reform since 2011, and Mr. Ryan considered applying it to those older than age 55.

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This would explain why the Romney campaign has chosen to attempt to distinguish the report from their plan (although there little to distinguish the Romney-Ryan Medicare plan from the model studied by Kaiser) rather than attack the findings of the Kaiser Family Foundation report.

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