How many times has the US Senate rejected the President's appointment of a cabinet member?

The U.S. Senate has rejected a president's appointment of a cabinet member only a few times in history. Notably, the most famous rejection occurred in 1989 when John Tower was denied confirmation as Secretary of Defense. Overall, there have been fewer than a dozen instances of cabinet-level nominations being rejected by the Senate. These rejections are relatively rare, reflecting the collaborative nature of the appointment process.