Political parties face a continuing challenge as they seek to create a majority. American society is always changing and they must respond. Yet fundamental issues endure and they must represent them. Parties have an existing base but they may need to seek new constituents as society changes. The challenge is to retain as much of the older base as possible while adding in new constituents. It is not an easy balancing act.

The enduring concerns have been economic, involving issues of promoting economic growth, fairness, and opportunity. Over time, the Republican Party has been the conservative party, arguing against government activity. Republicans believe that individuals can and should make it on their own. Too much government intrusion is bad for the economy and stifles growth. Democrats argue that class background, inequalities in opportunity, and the condition of the economy often affect the ability of individuals to succeed. They believe the government needs to take steps to increase equality of opportunity and provide some protection to individuals from the harm that could be done to them by corporations that often give a low priority to working conditions and employee well-being. Other issues, such as immigration, race, and moral and cultural concerns, have flared periodically, creating pressures for both parties to respond and address these concerns as well.

The challenge in understanding American political parties over time is to sort out how there could be continuity of many concerns while at the same time the composition of each party's electoral base has shifted significantly.