obstructionist

n.
One who systematically blocks or interrupts a process, especially one who attempts to impede passage of legislation by the use of delaying tactics, such as a filibuster.

obstructionism ob·struc'tion·ism n.
obstructionistic ob·struc'tion·is'tic adj.

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The noun has one meaning:

Meaning #1: someone who systematically obstructs some action that others want to take
  Synonyms: obstructor, obstructer, resister, thwarter

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