Because of polarization among Americans, the parties are more likely to nominate candidates who are ideological.
Explanation:
Polarization divides the population in two groups with different beliefs and philosophies altogether. In order to be on the safer side and expect both the groups vote for the party candidate, the parties nominate candidates who are ideological and bear the ability to attract both the polarized groups.
The parties ensure that they don't lose votes and eventually the elections merely for their candidate being inclined towards any of the polarized group.
