If any word characterizes the current Congress, it’s “obstruction.” The best-known tactic for blocking your political opponents is, of course, the filibuster, an antique tool that has seen such heavy use lately that critics have begun calling for it to be abolished.

If it is, though, the impulse is unlikely to die with it. The arcane procedural rules on Capitol Hill, especially in the Senate, offer legislators any number of obscure ways to thwart the plans of their opponents—and, says Bruce Oppenheimer, an expert on Congress at Vanderbilt University, some are already being considered as parties gird for more, and messier, battles. According to Oppenheimer and other observers, here are five to watch out for: