Much of politicians' energies are devoted to keeping the groups that support them happy. Usually that means continuing to take the same stands that they and their supporters have long championed. In the short term most groups' preferences change little, and as a result neither do the signals they send the politicians aligned with them.

Yet at times social or economic changes prompt old allies to make new demands of politicians. In such cases politicians may be forced to choose between their policies and their supporters. We should not be surprised that elected officials frequently are more attached to their allies, who mobilize voters and contribute to campaigns, than to their old policy positions. Such politicians are engaging in coalition maintenance. In these instances elected officials can claim consistency of a sort: consistent attentiveness to the concerns of a particular group.

The case of trade policy offers a clear illustration of the dynamics of coalition maintenance. Here we see a shift in parties' positions on an issue stemming from changing preferences by party-linked groups.