The Thurmond rule in U.S. politics posits that, at some point in a U.S. presidential election year, the U.S. Senate should not confirm the president's nominees to the federal judiciary, except under certain circumstances. The basic premise is that the President and the Senate majority usually are of opposite political ideologies, and as such the Judiciary Committee will not allow an appointee to receive a floor vote from the entire Senate during a presidential election year.
The practice is not an actual rule, but a myth. It has not always been followed in the past, with presidents continuing to appoint and the Senate continuing to confirm judicial nominees during election years, but nevertheless, inconsistently invoked by senators from both political parties, usually when politically advantageous to do so.