The answer is domestic events.
While presidential elections can influence congressional approval ratings, they do not have as direct or consistent an impact as domestic events. Presidential elections occur every four years and can shift public opinion, but they are not the most significant factor affecting congressional approval ratings on a regular basis.
Foreign events can affect congressional approval ratings, especially if they involve significant national security issues or international crises. However, their impact is often less immediate and less consistent compared to domestic events.
Supreme Court actions can influence congressional approval ratings, particularly when the Court makes controversial decisions. However, these actions are relatively infrequent and typically do not have as broad or sustained an impact as domestic events.
Domestic events, such as economic conditions, healthcare issues, social movements, and legislative actions, have the most direct and consistent impact on congressional approval ratings. These events are closely tied to the daily lives of constituents and can significantly influence their perceptions of congressional effectiveness and responsiveness.