Bush sought to expand Medicare so it would also cover the cost of prescription drugs, a program that became known as Medicare Part D. Many congressional Democrats opposed the bill because it did not allow Medicare to negotiate the prices of drugs, while many conservative Republicans opposed the expansion of the government's involvement in healthcare. Assisted by Speaker of the House Dennis Hastert and Senate majority leader Bill Frist, Bush overcame strong opposition and won passage of his Medicare bill. In December 2003, Bush signed the Medicare Prescription Drug, Improvement, and Modernization Act, the largest expansion of Medicare since the program's creation in 1965.