Final answer:
Congress tends to be most responsive to the initiatives of the President on broad issues of national importance, particularly in foreign policy and Supreme Court nominations.
Step-by-step explanation:
On broad issues of national significance, Congress is ordinarily most responsive to the initiatives of the President. The other entities such as the Supreme Court, the Speaker of the House, and the Senate Majority Leader also play significant roles in the political process. However, in the context of foreign policy, congressional leaders like the Speaker of the House and the Senate Majority Leader, as well as committee chairs, are regularly updated and consulted by the President's staff. They provide support and funding when necessary. Cooperation is particularly essential during Supreme Court nominations, requiring both presidential nomination and Senate confirmation. In divided government and partisan polarization, it is critical for presidents to work with Congress, targeting various audiences including Congress itself, party members, and sometimes the international community.