Final answer:
Congress is called upon to exercise its electoral duties during impeachment trials and every four years for presidential elections.
Step-by-step explanation:
Congress is called upon to exercise its electoral duties under the following circumstances:
- During impeachment trials: The House of Representatives brings charges of impeachment, and the Senate conducts the trial and decides whether the individual is to be removed from office.
- Every four years for presidential elections: General elections are held to choose members of Congress, and presidential elections are held every four years.