国会选举可能会跟总统选举一样激烈且一样重要，这是因为国会对制订法律起着关键作用。

与首席行政官来自议会的议会制不同，美国实行的是国会与总统分权制。总统和国会议员分别选举产生。虽然现任总统可以向国会提出立法议案，但这些议案必须由总统在国会内的支持者起草，并且，议案在送交总统签署之前必须经国会通过。参众两院在法律上和政治上独立于总统的意志。

与议会制相比，在国会内部不存在严格的党纪党规。国会议员在投票时可以支持他们认为最好的政策，包括最有利于自己连任的政策。其结果是，国会领袖为寻求多数支持就必须逐一争取议员，而无法依靠纪律严格的政党所自然提供的支持，每一次成功的立法都来之不易。由于国会以及议员权力巨大，立场难以预测，因此国会选举对整个国家来说具有重要意义。

众议院和参议院的差异

众议院和参议院拥有几乎相等的权力，但是两院的选举方式极为不同。建国先贤们的意图是让众议院接近公众，反映公众的意愿和愿望。因此，他们设计了规模较大的众议院，以便容纳众多来自小立法区的议员和频繁地(每两年一次)举行选举。最初，一些人认为两年任期为时太长。在交通运输依赖马匹的时代，在华盛顿的两年任期会使众议员在两年期间远离其选区。 今天的问题是，每两年举行一次选举使众议员差不多每个周末都得飞回各自的选区去巩固政治支持。

在众议院，一个席位代表了一个地理选区。如前所述，每个议员由本选区遵循简单多数原则选出，是该选区的唯一代表。50个州中的每一个州都在众议院内拥有至少一个席位，其余席位按人口分配给各州。例如，阿拉斯加州人口非常少，因此在众议院仅占一席。加利福尼亚州是人口最多的州，有53个席位。在每十年进行一次的人口普查之后，分配给每个州的席位根据该州在过去十年中的人口变化重新计算，州议会重新划定州内的选区边界，以反映分配给该州的席位的变化或州内的人口变化。

参议院的设计旨在由参议员代表较大的选区──即整个州，每个州无论人口多少享有同等代表权，因此小州和大州在参议院拥有同等影响(都推选两名参议员)。

参议员最早由州议会推选；直到1913年宪法《第17条修正案》通过后，才由各州选民直接选出。每一州有两名参议员，任期六年。每两年有三分之一的参议院席位改选，在州普选中获得多数选票的候选人当选。

忠于党还是忠于个人

过去，国会选举往往"以党为中心"，选民长期忠于某个政党，他们倾向于遵循党派界线投票，公职人员的个性和业绩对增加或减少选民的支持只有非常有限的影响。最近几十年，候选人的观点和个性在选举政治中变得越来越重要，在某种程度上降低了对党派忠诚程度的重要性。

自1960年代以来，联邦选举日益成为以候选人为中心的竞选。媒体和互联网的普及、大张旗鼓的筹款活动、频繁的民意调查以及其他现代竞选手段使选民可以对候选人有更多了解。因此，选民在决定支持谁的时候，往往要权衡候选人的长、短处和政党忠诚度。 二十世纪初期公共教育的普及和二次世界大战后高等教育的确立也使选民对自己的判断更有信心，因而在投票时更少听从党的提示。

以候选人为中心的竞选活动对国会现任议员非常有利，其连任获选率超过90%。部份原因是媒体对国会的温和报导，地方媒体对本州或本国会选区的议员更是赞许有加。现任议员由于得到这种基本上是正面的媒体渲染，并且每日处理公共政策问题以及在此过程中广泛接触力图影响政策的个人和团体，因而往往能够筹集到远远超过对手的竞选资金。出于这些以及其他原因，争取连任的议员──无论其政党归属──都非常有可能赢得选举。

Congressional Elections

House, Senate both central to lawmaking but have different election means

(The following article is taken from the U.S. Department of State publication USA Elections in Brief.)

Elections for the U.S. Congress can be as competitive and important as those for president. This is because of the central role that Congress plays in making laws.

Unlike a parliamentary system where the chief executive comes from the parliament, the American system, as noted, separates the legislature and the presidency. Presidents and legislators are elected separately. Although a sitting president may propose laws to Congress, they have to be drafted in Congress by his allies within that institution, and must be passed by the Congress before being sent back to the president for his signature. The House and Senate are legally and politically independent of the will of the president.

Within Congress, party discipline is less strictly observed in the American system than in parliamentary systems. It is fairly easy for members of Congress to vote on policies as they think best, including what they think best for winning their own reelection. As a result, congressional leaders must put together a winning coalition one member at a time, rather than count on automatic support from highly disciplined parties. This makes every congressional legislative victory difficult to obtain. Thus, Congressional elections are important to the nation, as Congress is powerful, and difficult to predict; and so are individual congressmen.

House and Senate Differences

The House and the Senate have nearly equal powers, but their means of election are quite different. The founders of the American Republic intended members of the House of Representatives to be close to the public, reflecting the public's wishes and ambitions. Therefore, the Founders designed the House to be relatively large in order to accommodate many members from small legislative districts, and to have frequent (two-year) elections. Originally, a two-year term was considered by some to be too long. In the days when transportation was by horse, a two-year term in Washington could keep a congressman away from his constituents for two years. Today, the concern is that elections every two years force congressmen to fly back to their districts every weekend or so to shore up political support.

Each House seat represents a unique geographic constituency, and, as noted above, every member is elected as sole representative from that district by plurality rule. Each of the 50 states is assured of at least one seat in the House, with the rest allocated to the states according to population. Alaska, for example, has a very small population and therefore holds only one seat in the House. California is the mostly highly populated state and holds 53 seats. Following each decennial census, the number of seats assigned to a state is recalculated to account for changes in state populations during the past 10 years, and state legislatures redesign congressional district boundaries within states to reflect changes in the number of seats assigned to the state or population shifts within the state.

The Senate was designed for its members to represent larger constituencies — the entire state — and to provide equal representation to that body of each state, regardless of population. Thus small states possess as much influence (two senators) as large states in the Senate.

Senators were originally selected by the state legislatures. It was not until enactment of the Seventeenth Amendment to the Constitution in 1913 that senators were directly elected by their state's voters. Every state has two senators elected for staggered six-year terms, with one-third of the Senate seats up for reelection every two years. A senator is chosen by plurality vote of the state electorate.

Loyalty to Party or Person

In the past, congressional elections tended to be "party centered," as many voters held long-term loyalties toward one political party or the other and tended to vote along party lines for Congress. The individual personalities and performances of office-holders may have only marginally added to or subtracted from voter support. In recent decades, the views and personalities of individual candidates have become more central to electoral politics and have somewhat diminished the importance of party loyalties.

Indeed, since the 1960s, national elections have become increasingly candidate-centered. The growth of the media and the Internet, the importance of aggressive campaign fundraising, constant opinion polls, and other aspects of modern campaigning have made the voter more aware of the candidate as an individual. As a result, voters tend to weigh individual candidate's strengths and weaknesses along with party loyalties in deciding whom to support. The establishment of broad-based public education in the early 20th century and of higher education after World War II has also made voters more confident of their own judgment; and less reliant on party cues with respect to ballot choices.

In this context of candidate-centered elections, incumbent members of Congress fare very well, with reelection rates well above 90 percent. This is partly due to often bland media coverage of Congress, and particularly coverage of individual members by local media in their states or congressional districts. With this generally favorable media exposure and daily involvement with public policy issues — and individuals and groups that seek to influence policy — incumbents also tend to raise far greater sums of money with which to campaign. For these reasons and more, incumbents who run for reelection are very likely to win, no matter which party they belong to.