Final answer:
Voters tend to change political parties in a divided government primarily due to dissatisfaction with government effectiveness during times of crisis, such as economic downturns or when personal safety is threatened, and due to increased polarization making governance challenging.
Step-by-step explanation:
What Triggers Voters to Change Political Parties in a Divided Government?
The issue that seems to trigger voters to change political parties in an era of divided government often has to do with the effectiveness of government and the ability of elected officials to accomplish policy goals. With the increase in political polarization, where Democrats and Republicans become more ideologically distinct, the efficiency of a divided government—where one party controls the presidency and the other controls one or both houses of Congress—tends to decrease. When major events, such as economic crises or significant social issues, trigger doubt in government efficacy or personal safety, people may shift their political allegiance.
Historically, notable shifts have occurred during times of crisis. For example, during the Great Depression, many voters abandoned the Republican Party in favor of the Democrats. More recently, increasing party polarization has made it difficult for moderate candidates and has led to more ideologically homogenous parties. This increasing polarization can lead to gridlock in governance, making it challenging for parties to enact major reforms or fulfill campaign promises, and thus potentially causing voter frustration and shifts in party allegiance.