Is there a name for a logical fallacy where person A criticizes X, and person B

Is there a name for a logical fallacy where person A criticizes X, and person B

Is there a name for a logical fallacy where person A criticizes X, and person B fallaciously assumes that because A criticizes X he must therefore subscribe to position Y, the presumed opposition of X, although A does not, in fact, take that position? For example, if A criticizes a Republican policy then B assumes that A must be a Democrat and staunch Obama-supporter,even though A is in fact a Republican himself, or else an Undeclared who regularly criticizes Obama as well.

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