Denzau and Munger (1986) argue that interest groups in general will seek out legislators whose
voters are indifferent to the policy that interest groups seek. Lohmann (1998) finds that
information asymmetry between general public and special interests is the fundamental cause of
policy bias and helps explain why interest groups often obtain their policy goals—even if they
are antithetical to those of the legislator’s constituents. In short, interest groups monitor
incumbent activities closely and the general public does not.
But again it is important to be reminded that it is the Congress that has the dominant role
in this relationship. Ainsworth (1997) too argues that “legislators structure their environment to
channel interest group influence and facilitate access for particular interests” (517).
Evidence of direct linkage between campaign contributions or PAC dollars and
congressional action is mixed, at best (see for example Grenzke 1989, Smith 1995).
Interestingly, research by economists has been more supportive of a connection than that of
political scientists—some of whom find a linkage and others do not (Wawro 2002). For example,
Stratmann (2002) examined behavior and contributions to the same Members of Congress over
two periods of time. He finds that changes in contribution levels did determine changes in roll
call voting. In an earlier work, Stratmann (1998) found that timing was important and that the
number of contributions increases when legislative events important to the contributor occur.
A number of political scientists have pointed out that it is not a direct vote, but rather
access, that groups purchase with their contributions and support, although access can be
difficult to measure (Leyden 1995).
Research has also documented that PAC contributions are motivated by long-term
investing in politicians. Snyder (1992) contrasted the PAC contributions over time of economic
Convention