First, because interest groups have stronger and more realistic opinions about public policies (advantageous or not). Second, they are reference of economic, political and religious positions that also involve or interfere in numerous public policies. And third, interest groups are able to pressure congressmen (legislators) on some issues considered as urgent by them.
<em>All interest groups share a desire to affect government policy to benefit themselves or their causes.</em>
The Hagia Sophia.
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