The confirmation bias is a well-known form of motivated reasoning that serves to protect an individual from cognitive discomfort. Hearing rival viewpoints or belief-opposing information creates cognitive dissonance, and so avoiding exposure to, or discounting the validity of, dissonant information are rational strategies that may help avoid or mitigate negative emotion. Because there is often systematic thought involved in generating the confirmation bias, deliberation tends to promote this behavioral bias. Nevertheless, the importance of negative emotion in triggering the need for this bias is underappreciated. This paper addresses a gap in the literature by examining mood and the confirmation bias in the political domain. Using results from two studies and three distinct decision tasks, we present data on over 1100 participants documenting the confirmation bias in different settings. All methods (recruitment and sample size, hypotheses, variables, analysis plans, etc.) were preregistered on the Open Science Framework. Our data show evidence of a confirmation bias across distinct dimensions of belief and preference formation. As hypothesized, the data show a strong increase in self-reported negative mood states after viewing political statements or information that are dissonant with one's political ideology. Finally, while not as robust across tasks, we report evidence that supports our hypothesis that negative mood will moderate the strength of the confirmation bias. Together, these results highlight the importance of mood response in understanding the confirmation bias, which helps further our understanding of how this bias may be particularly difficult to combat.