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general::
A problem so controversial and sensitive that it is risky to deal with. For example, Gun control is a political hot potato. This term, dating from the mid-1800s, alludes to the only slightly older expression drop like a hot potato, meaning "to abandon something or someone quickly" (lest one be burned). The idiom alludes to the fact that cooked potatoes retain considerable heat because they contain a lot of water.
American Heritage Idioms