Is any part of citizens' political "preferences" fixed? Is any part changeable? In this paper we argue that some kinds of "preferences" (basic issues and values) are relatively fixed, and that other kinds (ideological or party affiliation) are potentially fluid and malleable. We demonstrate this by adapting the theoretical spatial model of ideology to account for the introduction of a "new" issue. Basic parameters that influence the change in the voter's induced ideal point along the ideological dimension are derived. These include the difference between the status quo and the voter's ideal point on the new policy, the weight given the new policy in the voter's utility function, and size of the mapping between the policy and the prevailing ideology. The implications for political strategies are discussed, including a distinction that has not been made in previous work: issues accounted for by the existing ideological split change positions of candidates, while issues outside the prevailing ideology change the policy space itself.
