What is "opposition research"

n. (context politics English) A term for negative information retrieved about a candidate's opponent in an election for use in campaigning.

Opposition research (often referred to as oppo) is the practice of collecting information on a political opponent or other adversary that can be used to discredit or otherwise weaken them. The information can include biographical, legal or criminal, medical, educational, or financial history or activities, as well as prior media coverage, or the voting record of a politician. Opposition research can also entail using "trackers" to follow an individual and record their activities or political speeches.

The research is usually conducted in the time period between announcement of intent to run and the actual election; however political parties maintain long-term databases that can cover several decades. The practice is both a tactical maneuver and a cost-saving measure.

The term is frequently used to refer not just to the collection of information but also how it is utilized, as a component of negative campaigning.