As a back-up position, in 1965 Johnson turned his focus to hospital insurance for the aged under Social Security.[172] The key player in initiating this program, named Medicare, was Wilbur Mills, Chairman of the House Ways and Means Committee. To reduce Republican opposition, Mills suggested that Medicare be fashioned as a three-layer cake: hospital insurance under Social Security; a voluntary insurance program for doctor visits; and an expanded medical welfare program for the poor, known as Medicaid.[173] The bill passed the house by a margin of 110 votes on April 8. The effort in the Senate was considerably more complicated; however, the Medicare bill passed Congress on July 28 after negotiation in a conference committee.[174] Medicare now covers tens of millions of Americans.[175] Johnson gave the first two Medicare cards to former President Harry S Truman and his wife Bess after signing the Medicare bill at the Truman Library in Independence, Missouri.