Read the text and explain why the U.S. has a two-party system.

Political parties serve four essential functions and in serving these functions, the parties allow the United States to approach the ideal of democracy more closely. The first and most important function of an American party is to organize elections by nominating candidates and seeking office. The second function is to build coalitions by attracting group support. Thirdly, parties work to simplify political choices. Finally, they organize government and policy making, attempting to use the institutions of government to reflect the will of the voters.

Today, the Republican and Democratic parties are the two main political parties in the United States. Most elected officials serving as president, congressional representative, state governor or state legislator are members of one of these parties. In a November 2006 Gallup Poll (a leading barometer of public opinion operated by the Gallop Organization), approximately 59 percent of Americans identified themselves as either Republicans or Democrats.

Compared to political parties in other democratic nations, political parties in the United States tend to have relatively low internal unity and lack strict adherence to an ideology or set of policy goals. Generally, Republicans have tended to support limiting federal powers and protecting the authority of state and local governments, to take a conservative approach to taxation and spending, and to oppose government interference with free enterprise. In contrast, Democrats have tended to take a more expansive view of the powers of the federal government, to support raising and spending money to address social ills on a national basis, and to favor federal regulation as a tool to improve business practices.

Scholars do not entirely agree on why the two-party system should be a feature of American political life, but two kinds of explanations are of major importance. The first has to do with the system of elections, the second with the distribution of public opinion.

Elections at every level of government are based on plurality, winner-take-all method. The plurality system means that in all elections for representative, senator, governor and president, and in almost all elections for state legislator, mayor and city councillor, the winner is that person who gets the most votes, even if they do not constitute a majority of the votes. Winner-take-all rules trigger a cycle that leads to and strengthens a system of few (two in the U.S.) political parties. Since elections are won by the single candidate who garners the most votes, third party candidates have a serious disadvantage.

The second kind of explanation for the persistence of two parties is to be found in the opinions of the voters. The American two-party system results in part from the relative absence of irreconcilable differences within the American electorate about basic social, economic, and political institutions. Most of the time most citizens have agreed enough to permit them to come together into two broad coalitions. The other key factor is the huge influence of money in the American electoral system. Since effectively a candidate can spend any amount he can raise (not allowed in many other countries) and since one can buy broadcasting time (again not allowed in many countries), candidates of any other party face a formidable financial barrier to entry.

Despite broad political influence of the Democratic and Republican parties, the so-called “third” parties and independent candidates remain a feature of American politics. Most third parties have tended to flourish for a single election and then die, fade, or be absorbed into one of the major parties. There is evidence that third parties can have a major impact on election outcomes. For example, a third-party candidate might draw votes away from the candidate of the party more closely aligned with to the position of the third-party candidate, thus enabling the other party to win the election – often without receiving a majority of the vote.

Although once powerful, America's political parties now seem to be in a state of decline. More and more, Americans express their dislike of the two-party system and the small range of choice which it allows. Numerous polls taken in recent years indicate that Americans are hungry for a third party to rival the Republicans and Democrats. The parties are moving closer together on a wide variety of issues, and people no longer feel that the parties give them two distinct choices on election day.