Scholars have debated the importance of declining political trust to the American political system. By primarily treating trust as a dependent variable, however, scholars have systematically underestimated its relevance. This study establishes the importance of trust by demonstrating that it is simultaneously related to measures of both specific and diffuse support. In fact, trust's effect on feelings about the incumbent president, a measure of specific support, is even stronger than the reverse. This provides a fundamentally different understanding of the importance of declining political trust in recent years. Rather than simply a reflection of dissatisfaction with political leaders, declining trust is a powerful cause of this dissatisfaction. Low trust helps create a political environment in which it is more difficult for leaders to succeed.