When the Founders of the American Republic wrote the U.S. Constitution in 1787, they did not envision a role for political parties in the governmental order. Indeed, they sought through various constitutional arrangements — such as separation of powers, checks and balances, federalism, and indirect election of the president by an electoral college — to insulate the new republic from political parties and factions.

In spite of the Founders' intentions, the United States in 1800 became the first nation to develop parties organized on a national basis and to transfer executive power from one faction to another via an election.

The Emergence and Pervasiveness of Political Parties

The development of political parties was closely linked to the extension of the suffrage as qualifications requiring property ownership were lifted during the early 1800s. With a vastly expanded electorate, a means was required to mobilize masses of voters. Political parties became institutionalized to accomplish this essential task. Thus, parties in America emerged as a part of this democratic expansion, and, by the 1830s, they were a firmly established part of the political firmament.

Today, the Republican and Democratic parties pervade the political process. Approximately 60 percent of Americans consider themselves either Republicans or Democrats, and even those who say that they are independents normally have partisan leanings and exhibit high levels of party loyalty. For example, in the five presidential elections between 1980 and 1996, 75 percent of independents who "leaned" toward the Republicans or Democrats voted for their preferred party's presidential candidate. And in 2000, 79 percent of Republican "leaners" voted for Republican George W. Bush, while 72 percent of Democratic "leaners" cast ballots for the Democratic candidate, Al Gore.

The pervasiveness of partisan influences also extends to the party in government. The two major parties now dominate the presidency, Congress, the governorships, and the state legislatures. Every president since 1852 has been either a Republican or a Democrat, and in the post-World War II era, the two major parties' share of the popular vote for president has averaged 94.8 percent. After the 2002 congressional and local elections, there was one lone independent senator among the 100 members of the U.S. Senate, and just two of the 435 representatives in the U.S. House of Representatives were independents. At the state level, all 50 governors were either Republicans or Democrats, and only 21 (.003 percent) of more than 7,300 state legislators were elected as other than Republicans or Democrats. It is the two major parties that organize and dominate government at both the national and state levels.

Although American parties tend to be less ideologically cohesive and programmatic than parties in many democracies, they do play a major and often decisive role in shaping public policy. Indeed, since the 1994 elections, congressional Republicans and Democrats have demonstrated sharp policy differences and an unusually high level of intra-party unity compared to historic norms. The policy disagreements between the two parties exist within a context of congressional and senatorial elections every two years that have real potential to result in a change in partisan control of the House of Representatives and the Senate. The combination of policy divisiveness and intense competition for chamber control has created in recent years a super-heated atmosphere of partisan conflict in both the Senate and the House. And in the run-up to the 2004 elections, the congressional leaders of both parties and the candidates for the Democratic presidential nomination, as well as the Bush administration, have engaged in a continuing series of maneuvers designed to gain electoral advantage.

Why a Two-Party System?

Two-party competition stands out as one of the American political system's most salient and enduring features. Since the 1860s, the Republicans and Democrats have dominated electoral politics. This unrivaled record of the same two parties continuously monopolizing a nation's electoral politics reflects structural aspects of the political system as well as special features of American political parties.

The standard arrangement for electing national and state legislators in the United States is the "single-member" district system. What this means is that whoever receives a plurality of the vote (that is, the greatest number of votes in any given voting district) is elected. Unlike proportional systems, the single-member district arrangement permits only one party to win in any given district. The single-member system thus creates incentives to form two broadly based parties with sufficient popular appeal to win legislative district pluralities, while condemning minor and third parties to almost perpetual defeat — not a prescription for longevity unless they can combine forces with a major party. Combining forces with a major party, however, is not an option for most minor parties because all but a handful of states ban so-called fusion tickets in which a candidate runs as the nominee of more than one party.

A further institutional nudge toward two-partyism is provided by the electoral college system for choosing presidents. Under the electoral college system, Americans technically do not vote directly for a presidential slate of candidates. Instead, they vote within each state for a slate of "electors" who are pledged to one or another presidential candidate. Election as president requires an absolute majority of the 50 states' 538 electoral votes. This requirement makes it extremely difficult for a third party to achieve the presidency because the individual states' electoral votes are allocated under a winner-take-all arrangement. That is, whichever candidate receives a plurality of the popular vote in a state — even if it is just a narrow plurality — wins all of that state's electoral votes. Like the single-member district system, the electoral college works to the disadvantage of third parties, which have little chance of winning any state's electoral votes, let alone carrying enough states to elect a president.

With the Democrats and Republicans in control of the governmental machinery, it is not surprising that they have created other electoral rules that work to the advantage of the major parties. Just getting a new party's name on the ballot within the states can be an arduous and expensive undertaking. For example, the state of North Carolina requires a petition containing 58,842 voters' signatures in order for a new party to place its presidential candidate on the state's ballot for the 2004 election. In addition, the Federal Election Campaign Act bestows special benefits on major parties, including public funding of presidential campaigns at a substantially higher level than is available to minor parties — even those that reached the qualifying threshold of 5 percent of the popular vote in the last election.

America's distinctive nominating process is an additional structural barrier to third parties. Among the world's democracies, the United States is unique in its reliance on primary elections to nominate partisan candidates for congressional and state offices and its use of state-level presidential primaries in the selection of presidential nominees. Under this type of nominating system, rank-and-file voters in a primary election select their party's nominee for the general election. In most nations, partisan nominations are controlled by the party organizations and their leaders. But in the United States, it is the voters who make the ultimate determination of who the Republican and Democratic nominees will be.

Although this system helps create weaker internal party organizations than is the case in most democracies, this participatory nominating process has also contributed to the Republican-Democratic domination of electoral politics for almost 150 years. By winning party nominations through primary elections, insurgents can gain access to the general election ballot and thereby enhance their chances of general election victories without having to organize third parties. Thus, the primary nomination process tends to channel dissent into the two major parties and makes it generally unnecessary for dissidents to engage in the difficult business of forming a third party. Of course, the system of primary elections to nominate candidates also makes the two major parties highly permeable and occasionally penetrated by various "fringe" social movements and "outsider"-type candidates.

Broad-Based Support and Centrist Positions

American parties are multi-class and broad based in their electoral support. With the exception of African-American voters — 90 percent of whom voted for the Democratic presidential candidate in 2000 — both the Republican and Democratic parties draw significant levels of support from virtually every major socioeconomic group in society. Although members of labor-union households, for example, are commonly thought to be Democrats, the Republicans can expect in most elections to receive at least one-third of the labor union vote, and in 1984, the party received 46 percent of the union vote. In 2000, union households voted 37 percent Republican. Similarly, while support for Democrats normally declines as income levels go up, Democratic presidential candidates can usually expect substantial support from upper-middle-class voters. In 2000, for example, Democratic candidate Al Gore received 43 percent of the vote among persons whose annual family income was more than $100,000.

Political parties in the United States also exhibit relatively low internal unity and lack strict adherence to an ideology or set of policy goals. Rather, they have traditionally been concerned first and foremost with winning elections and controlling the personnel of government. Given their broad socioeconomic bases of electoral support and the need to operate within a society that is largely middle-of-the-road ideologically, American parties have adopted essentially centrist policy positions. They have also demonstrated a high level of policy flexibility. This non-doctrinaire approach enables the Republicans and the Democrats to tolerate great diversity within their ranks, and it has contributed to their ability to absorb third parties and protest movements when they have occurred.

Decentralized Political Parties

It is hard to overstate the extent to which American parties are characterized by decentralized power structures. Historically speaking, within the party-in-the-government, presidents cannot assume that their party's members in Congress will be loyal supporters of presidential programs, nor can party leaders in Congress expect straight party-line voting from members of their party. Within the party organization, the Republican and Democratic congressional and senatorial campaign committees (composed of incumbent legislators) operate autonomously from the presidentially oriented national party committees — the Republican and the Democratic National Committees. In addition, except for asserting authority over procedures for selecting delegates to national nominating conventions, national party organizations rarely meddle in state party affairs. This level of organizational fragmentation reflects, in part, the consequences of the constitutional separation-of-powers system — the division of powers among the legislative, executive, and judicial branches of government, with each branch selected by different procedures, having different terms of office, and independent of one another. This system of divided governmental powers creates only limited incentives for party unity between legislators and their party's chief executive. This is broadly true whether we are talking about members of Congress vis-?is a president of their own party, or a similar relationship between state legislators and a governor.

The constitutional principle of federalism, which has created a layered system of federal, state, and local governments in the United States, further decentralizes the parties by creating thousands of constituencies — also at the federal, state, and local levels — each with its own officeholders. As previously noted, the use of primary elections to nominate candidates also weakens the party organizations by denying them the ability to control the selection of party nominees. Individual candidates, therefore, are encouraged to build their own personal campaign organizations and electoral followings, first to win the primaries and then the general elections. Even campaign fund-raising is largely the personal responsibility of the individual candidates, since party organizations normally have limited financial resources and are often severely restricted by law in terms of how much money they contribute, especially to federal election campaigns.

Americans' Misgivings About Political Parties

In spite of the long and impressive evidence of partisanship within the American political system, an ingrained component of the American civic culture is a distrust of political parties. The adoption of the primary system for nominating congressional and state candidates early in the 20th century, and the more recent proliferation of presidential primaries, which have become the determining factor in presidential nominations, are testimony to anti-party sentiment within the public. Americans are uncomfortable with the leaders of their party organizations exercising great power over their government. Public opinion polls consistently reveal that large proportions of the electorate believe that parties do more to confuse the issues than clarify them — and that it would be better if there were no party labels on the ballot.

Not only do American parties operate in a generally inhospitable cultural climate, but they are also faced with the problem of a substantial number of voters attaching diminished importance to their party identification. One indicator of this weakened sense of partisan attachment on the part of voters is the incidence of ticket-splitting — voting for candidates of different parties in the same election. Thus, in 2000, 20 percent of voters split their ballots by voting for candidates from different parties for president and for the U.S. House of Representatives. As a consequence, 40 of the House of Representatives' districts carried by George W. Bush in the presidential election were at the same time won by Democratic House candidates.

As a result of many Americans having relatively weak partisan commitments, the existence of a sizeable segment of the voters who consider themselves independents, and the tendency of a significant percentage of citizens who engage in split-ticket voting, American politics is candidate centered rather than party centered. This has meant that divided party control of the executive and legislative branches of government has become a commonplace feature of both the national government and the 50 states. Thus, in all but four years since 1980, the presidency and at least one chamber of the Congress have been controlled by different parties. Twenty-nine states (58 percent) had divided party control after the 2002 elections.

Third Parties and Independent Candidates

As the accompanying table indicates, third parties and independent candidates, despite the obstacles discussed previously, have been a periodic feature of American politics. Often they have brought societal problems that the major parties were failing to confront to the forefront of public discourse — and onto the governmental agenda. But most third parties have tended to flourish for a single election and then die, fade, or be absorbed into one of the major parties. Since the 1850s, only one new party, the Republican Party, has emerged to achieve major party status. In that instance, there was a compelling moral issue — slavery — dividing the nation that provided the basis for candidate recruitment and voter mobilization.

Although the table does not provide much support for the long-term viability of third parties, there is evidence that these parties can have a major impact on election outcomes. For example, Theodore Roosevelt's third-party candidacy in 1912 split the normal Republican vote and enabled Democrat Woodrow Wilson to be elected with less than a majority of the popular vote. In 1992, H. Ross Perot's independent candidacy attracted voters who, in the main, had been voting Republican in the 1980s, and thereby contributed to the defeat of the incumbent Republican president, George H.W. Bush. In the extremely close 2000 contest between Republican George W. Bush and Democrat Al Gore, it is possible that had Green Party candidate Ralph Nader not been on the ballot in Florida, Gore might have won that state's electoral votes and thereby gained the majority of the electoral votes needed to be elected president.

Public opinion surveys since the 1990s have consistently shown a high level of popular support for the concept of a third party. In the run-up to the 2000 election, a Gallup Poll found that 67 percent of Americans favored a strong third party that would run candidates for president, Congress, and state offices against Republican and Democratic nominees. It is just such sentiments, plus lavish campaign spending, that enabled Texas billionaire Perot to gain 19 percent of the popular vote for president in 1992, the highest percentage for a non-major-party candidate since Theodore Roosevelt (Progressive Party) won 27 percent in 1912.

In spite of demonstrations of potential support for a third party, imposing barriers exist to a third party's winning the presidency and even electing a substantial number of senators or representatives. In addition to those noted previously, the most significant is the fear among voters that if they vote for a third party candidate, they will, in effect, be "wasting" their votes. Voters have been shown to engage in strategic voting by casting ballots for their second choice when they sense that a third-party candidate has no chance of winning. Thus in the 2000 election, 15 percent of voters in a pre-election survey rated Ralph Nader more highly than either George W. Bush or Al Gore, but Nader received only 2.7 percent of the popular vote. Similarly in 1992, among voters ranking Ross Perot highest, 21 percent defected to other candidates when they actually cast their ballots.

There is also the phenomenon of "protest" voting for third-party candidates. For example, Gallup Polls in 1992 revealed that 5 percent of Perot's voters said that they would not have voted for him if they thought he could win.

Third party and independent candidates would also face a potentially daunting post-election problem if they won the presidency. This, of course, is the problem of governing — staffing an administration and then working with a Congress dominated by Republicans and Democrats who would have only limited incentives to cooperate with a non-major-party president.