Final answer:
The increase in presidential power after 1945 is attributed to factors like US involvement in global affairs, Cold War tensions, domestic issues, and public expectations, but not by legislation on impounding funds.
Step-by-step explanation:
Factors Contributing to the Increase in Presidential Power After 1945
Several key factors have contributed to an increase in presidential power in the post-1945 era. These include the increasing US involvement in international affairs, which has placed the president in a central role as diplomat-in-chief and commander-in-chief. The tensions between the US and the Soviet Union during the Cold War period further elevated the president's role in foreign policy decisions and national security. Economic and domestic problems such as inflation, unemployment, and civil rights issues have prompted the public to expect more federal intervention, leading to increased presidential involvement in these matters. Likewise, an increase in public expectations for services from the federal government has played a part in expanding the executive's reach and responsibilities. Among the options, the one that has not contributed to an increase in presidential power is 'legislation granting the president the power to impound funds appropriated by Congress,' as this generally signifies an attempt by the legislative branch to limit the executive's power over federal spending.