Obstructionist

noun

1. 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.
2. One who factiously opposes and hinders the action of others; specifically, one who systematically, persistently, and factiously hinders the transaction of business in a legislative assembly; an obstructive; a filibuster.
3. One who deliberately hinders progress; one who obstructs business, as in a legislative body.
4. someone who systematically obstructs the actions of others
5. someone who attempts to impede the progress of legislation