Since the Vietnam War, Congress has played a more active and public role in the foreign policy process. The ability of Congress to make foreign policy, however, is constrained by many strategic, ideological, situational, and electoral factors. In addition, the relationship between Congress and the president is often filled with conflict, leading to gridlock and chaotic policy making on a variety of international issues, from military intervention to foreign aid. As this chapter highlights, Congress has the ability to influence procedural aspects of foreign policy, such as which actors are involved and how they participate, as well as a number of other tools at its disposal to influence the foreign policy agenda. The power of the purse is the most important way in which legislators influence foreign policy, as well as constitutional checks on the executive branch’s war powers.

Consensus between the president and Congress on foreign policy issues has ebbed and flowed, with the post-Cold War period marked by a lack of cooperation between the two. Congressional committees and representatives have become increasingly involved in foreign policy making, with the Senate judiciously exercising its constitutional power to provide “advice and consent” to the president. The situational context of Congress in terms of its relationship with the White House ranges from compliance to independence. This context of the relationship depends largely on the particular foreign policy issue, the broader domestic and international climates, and timing factors. For example, during the 1990s, President Clinton faced an increasingly resistant Congress and a new isolationist ideology. Yet, as this chapter reviews, the terrorist attacks of September 11 led to bipartisan deference to the president on foreign policy. During the Obama administration, a divided Congress has led to several challenges on foreign policy issues. Congress continues playing an oversight role in the foreign policy process by passing legislation that determines how the president and bureaucracy conduct foreign affairs, such as the War Powers Resolution and the Intelligence Oversight Act.

Congress, like the president, is not free and independent in its efforts to shape foreign policy. Divided by party politics, legislators often face policy gridlock and confusion. Congress is a highly fragmented institution with its two chambers, multiple committees and subcommittees, and perpetual electoral concerns, further complicating its ability to successfully influence the foreign policy agenda.

However, despite these structural limitations and the large number of actors, Congress has been successful in foreign policy making by influencing government procedure: it has created institutions (such as the Congressional Budget Office), restructured agencies (like the State Department), and placed conditions on agencies (for example, requiring the Defense Department to report on current military involvement). Procedural reforms are not always successful: the War Powers Resolution has had mixed success in its aim to involve Congress in the foreign policy process. Congress also manages and approves the budgetary aspects of foreign affairs, such as the recent increases in defense spending and continual downturns in international affairs spending. Since the September 11 attacks, Congress has begun to combine domestic and international policies, such as in the USA PATRIOT Act.