“In the Civil Rights era of the 1960s and early 1970s, public opinion shifted towards the problem of the uninsured, especially the elderly. Since care for the elderly would someday affect everyone, supporters of health care reform were able to avoid the worst fears of “socialized medicine,” which was considered a dirty word for its association with communism. After Lyndon B. Johnson was elected president in 1964, the stage was set for the passage of Medicare and Medicaid in 1965. Johnson’s plan was not without opposition, however. “Opponents, especially the AMA and insurance companies, opposed the Johnson administration’s proposal on the grounds that it was compulsory, it represented socialized medicine, it would reduce the quality of care, and it was ‘un-American.'” These views notwithstanding, the Medicare program was established by legislation signed into law on July 30, 1965, by President Lyndon B. Johnson.”
Read more about the history of health care reform in the United States in Wikipedia.