The statement that best explains why this use of the president's bully pulpit power is weak is:
The president is addressing a foreign audience.
While it is important for the president to communicate their vision, delivering a speech to foreign leaders does not have the same impact as addressing the American public or Congress. The effectiveness of the bully pulpit is typically stronger when communicating to domestic audiences, where the president can mobilize public opinion and influence legislative action more effectively. Additionally, foreign leaders may have differing interests, and unilateral declarations may not resonate or be actionable within the context of global diplomacy.