Advocacy groups have definitely added confusion to the lawmaking process. From how the lawmakers behave to how they are percieved by the public as a result of the unchecked spending of these groups, it is now much harder to get a real sense of what is going on in government.
Many advocacy groups score legislatures on their voting record and when it comes time for elections, these scores are used to determine how the group will promote or campaign against each lawmaker. Often times the groups will make a big deal when legislation is being considered to make sure lawmakers know if they are being "scored" or not, and this alone can heavily influence the way the votes go.
Advocacy groups have distorted the legislative process in Congress. Special interest groups use different tactics to try to persuade congress to enact legislation that is beneficial to their agenda. Some Advocacy groups use illegal methods to try to achieve their gains, such as bribery, fraud and other forms of corruptions. Another tactic that is used by Advocacy groups is the use of protesters to cause social unrest.
I think that advocacy groups have ruined the legislative process in Congress. So many of these groups have such a huge political agenda that they ignore what is best for the people and delay laws getting passed. I think that the whole political structure needs to be seriously re-evaluated to save this country.