It should be noted that political parties and interest groups have a great influence on public policy.
A political party is composed of people who have similar political beliefs and aims. The candidates from this organized group aspire to be elected and thereby influence public policy.
An interest group has no intention of getting its members to hold government positions. It simply influences public policy by mainly lobbying.
Interest groups have a greater impact on determining and shaping public policy as they represent businesses and corporations.They also influence people through media campaigns.
