We study a model in which political parties can increase the importance of specific policy issues. Voters have ideal positions in a multidimensional policy space and give different weights to various issues. Two political parties compete both in choosing policy positions and manipulating the weight of each issue. This competition severely alters political interactions. First, it typically increases the divergence among voters and between policy positions. Second, under symmetry, in equilibrium each party selects a distinct dimension to align closer with voters and emphasize in electoral campaigns while maintaining divergent positions on all other dimensions. The model also predicts a newcomer advantage and significant effects from increasing the ability to target advertising.