flows from something else, not a gun, but just as deadly. Actually more than one thing:

#1 Money (Got any campaign contributions? Buy/Rent a politician.)
#2 Power (Who they influence who they control)
#3 Greed (If they pass those laws, will the companies they have invested in be able to profit from them?)
#4 Sloth (Take their time, use anything to delay the law getting passed. Make it look like they are doing their job.)
#5 Lust (They spent the money on whores and booze, got caught and someone is blackmailing them to vote a certain way.)
#6 Pride (They let their pride get in the way of doing the right thing for the citizens they represent.)
#7 Envy (They envy the other states, or other group of people, so they try to get laws changed to affect those states or groups.)
#8 Hate (Goes with #7, but they hate due to their bigoted ways.)
#9 Issues (They know the issues, and usually side one way or the other. But they will waffle, if it means that they will get something from the above reasons.)
#10 Stupidity (Which is making decisions for reasons that no intelligent person can understand.)

Those are the top ten that I can think of off the top of my head.