When H.R. 6675 reached the Senate, the risk to the bill came from liberals eager to expand coverage by adding amendments to the bill. One such amendment added to the bill by the Senate Finance Committee shifted coverage of specialized medical services from Part B to Part A. On July 19, 1965, the Senate passed an amended bill by a 68 to 21 roll call vote with a cost of approximately $800 million more than the House-passed bill. Representative Mills, with the backing of administration officials, dominated the conference and eliminated practically all of the Senate amendments. The conference report was agreed to by lop-sided votes in the House on July 27 and in the Senate on July 28. On July 30, President Johnson signed Medicare into law at a ceremony at the Harry S. Truman Presidential Library with the former president by his side.

United States. Congress. Senate. Committee on Finance. "Amendment to H.R. 6675." Amendment to H.R. 6675, April 13, 1965; “H.R. 6675, 1 of 3” folder, Box 3; Committee on Finance; 89th Congress; Records of the U.S. Senate, RG 46; National Archives.. Accessed 20 April 2024. https://acsc.lib.udel.edu/items/show/196.