Prior to Medicare, seniors could only get full health insurance coverage at an extreme cost. Most seniors had only partial coverage or none at all. Full coverage in the private sector was not an option for most seniors, just as full coverage in the private sector is not an option for millions of Americans today.
Republicans, however, opposed Medicare and have always described it as one of the main problems of LBJ's administration -- joining social security enacted during FDR's administration. According to the conservative script, Medicare = social security = welfare = evil "entitlement programs," enacted by "big government" and "big spending" liberal Democrats. Today, however, Republicans are pretending to favor Medicare, while generally describing public plans as socialized medicine. Seniors should find this approach insulting. Sane Republicans should find it embarrassing.
Possible Part II: Veterans Administration = Public Plan = Government-Run Health Program = Government-Sponsored Health Plan.