Final answer:
The president does not exercise one of their formal powers when attending a campaign rally to support a candidate from their political party.
Step-by-step explanation:
The correct answer is D. The president attends a campaign rally to support a candidate from their political party. This scenario does not involve the president exercising one of their formal powers. Attending a campaign rally is a political activity and not a formal power granted to the president by the Constitution.
On the other hand, signing a bill into law (option A), delivering the State of the Union Address (option B), and negotiating a treaty (option C) are all examples of the president exercising their formal powers.