House Republicans are still finalizing their formal blueprint for government spending over the next ten years. But, on Fox News Sunday, Budget Committee Chairman Paul Ryan confirmed what several media outlets reported last week: The Republicans will propose to transform Medicare from a government-run program into what most people would call a voucher system. They will also propose to convert Medicaid from an entitlement to a block grant.

These would be huge, controversial changes. And while Ryan says his party is actually trying to “save Medicare [and] save Medicaid,” I know of at least one person who would be skeptical: Lyndon Johnson.

Johnson was the president who, in 1965, signed the legislation creating Medicare and Medicaid: “No longer will older Americans be denied the healing miracle of modern medicine," Johnson said at the signing ceremony. "No longer will illness crush and destroy the savings that they have so carefully put away over a lifetime so that they might enjoy dignity in their later years.”

Read those quotes carefully, because they spell out the covenant that Johnson made with the American people on that day: A promise that the elderly and (certain groups) of the poor would get comprehensive medical insurance, no matter what.

Will the new Republican plan faithful to that covenant? We haven’t seen the details, obviously, so it's impossible to know. But Ryan told Fox News that the proposal for Medicare will be very similar to the one he crafted with Alice Rivlin, former director of the Congressional Budget Office and then the Office of Management and Budget.