The bicameral, national legislature of the United States. According to Article I, Section 1 of the Constitution, ‘All legislative powers herein granted shall be vested in a Congress of the United States, which shall consist of a Senate and House of Representatives’. The Senate has a hundred members, two from each state, elected for six-year terms in two-year cycles of staggered elections under first-past-the-post arrangements. First-past-the-post also applies in the election of 435 members of the House of Representatives. Representatives are elected to simultaneous two-year terms with the number of seats per state determined by the size of the population, although every state is entitled to at least one member. A redistribution of House seats occurs after each decennial census (see apportionment), and, within the states, the determination of congressional boundaries is the responsibility of the state legislatures.

The House and the Senate are co-equal in status, but nevertheless different institutions. All bills must pass both houses and, since the passage of the Seventeenth Amendment in 1913, the members of both have been popularly elected (previously, senators were chosen by the state legislatures). The two-year term tends to tie members of the House of Representatives more closely to their constituents, whereas senators enjoy not only more independence, but also greater visibility. The larger membership of the House requires more formal organization than in the Senate, where a club-like atmosphere traditionally prevails. In financial matters, the House lays claim to superiority on the strength of Article I, Section 7 of the Constitution, which states that ‘All Bills for raising Revenue shall originate in the House of Representatives’. Meanwhile, the Senate draws on its constitutional prerogatives in treaty-making to support assumptions of primacy in foreign affairs. Its role in confirming presidential appointments (especially to the judiciary) is likewise a source of its power.

The United States Congress is often characterized as the most powerful legislature in the world. It has, undoubtedly, lost ground to the executive branch in the twentieth century, but, as many recent Presidents would confirm, it is far from being reduced to the position of impotence that has befallen many of its counterparts elsewhere. There are three related phenomena that help to account for this: the Constitution, American political parties, and congressional committees.

In drawing up the Constitution the Founding Fathers were bent on ensuring that too much power did not fall into too few hands. Accordingly they devised a complex system of checks and balances which to this day provides for ‘separated institutions sharing powers’. Modern Presidents are expected to lead in both foreign and domestic policy-making, but Congress, from which members of the executive branch are excluded, constitutes an awesome obstacle to the fulfilment of those responsibilities. The appointment of executive officials is subject to the ‘Advice and Consent of the Senate’; every bill, every demand for revenue, and every request for expenditure must be approved by a body marked by a centrifugal distribution of power and notorious for its unwillingness to act as a mere ‘rubber stamp’.

In parliamentary systems, it is possible for strong parties, with significant leaders and disciplinary means, to bring order to the legislature and thereby facilitate executive dominance. No such parties exist in the United States Congress. There are parties and party leaders, but the ability of the latter to control members is limited. Party loyalty in Congress is a most fragile commodity. The seniority system, which for a long time substituted for party as an organizing device, was seriously weakened by reforms of procedure after Watergate.

The weakness of party helps to explain the potency of congressional committees, the great powerhouses of the national legislature in the United States. More than a century ago Woodrow Wilson noted that ‘Congress in session is Congress on public exhibition, whilst Congress in its committee rooms is Congress at work’. This is no less true today. Debates on the floor of either chamber are rarely meaningful; the fate of legislative proposals is decided in specialist committees; it is here where the great issues are thrashed out, where the executive is called to account and where policy is made. In other systems committees are chaired by party loyalists and voting takes place along party lines, but congressional committees are institutions of a quite different order.

— David Mervin