“Medicare Part E” where the “E” represents “everybody.” Just let any citizen in the US buy into Medicare. A real “public option”.
Just pass a simple bill, like when Medicare was expanded to include disabled people – that says that any American citizen can buy into the program at a rate to be set by the Centers for Medicare and Medicaid Services (CMS) and the Department of Health and Human Services (HHS) which reflects the actual cost for us to buy into it - a sliding scale perhaps. Add a little extra to make sure we cover costs in perpetuity for elders and disabled.
It'll need a few fixes, like letting there be negotiation for drug prices; letting go of the Medicare Part C allowances for supplemental insurances - no longer needed.
[All credit for this idea to Thom Hartmann]