A "flip-flop" (used mostly in the United States) or a U-turn (used in the United Kingdom) is a sudden real or apparent change of policy or opinion. Usually it will occur during the period prior to an election in order to maximize the candidate's popularity.

Example 1: "Candidate A, after finding out that weapons of mass destruction won't likely be found in Iraq, quickly changed his stance in order to keep Candidate B from using his previous stance against him."

Example 2: "During his previous campaign, Candidate B promised to regulate the greenhouse gas carbon dioxide as a pollutant, but declined to do so after taking office. Candidate A could now cite this as a flip-flop."

This term has it's most known use in the 2004 U.S. presidential election campaign. Initially, it was used by Republicans as a catch-phrase attack on John Kerry for "flip-flopping" on the issues. By the end of the race, the term was also being used by Democrats to attack George W. Bush in the same way.

See also: Election promise