Thursday night millions of Americans watched the first of the three televised presidential debates between Democratic Party nominee John Kerry and Republican Party nominee George Bush. Independent candidate Ralph Nader did not qualify to participate in the debate and neither did a member of any smaller party. Zlatica Hoke looks at why only two parties have dominated much of America?s political history.

Almost alone in the world, the American two-party system has been in place since George Washington?s time when the Federalists and the Republicans became the country?s first political groups. The two major parties have changed over time, but very rarely has a third party unseated one of them.

Bruce Larson, professor of political science at Fairleigh-Dickinson University in Madison, New Jersey, says the two-party system is a result of the American system of voting: ?Unlike many democracies in the world, the United States has what are called winner-take-all elections.? In theory, this means that a candidate for a political office could win elections with only two votes as long as all of his opponents got only one.

In countries with a parliamentary system, the number of votes a party receives determines the size of that party?s representation in the legislature. Professor Larson says this system encourages small parties to field candidates because they have a good chance of winning at least some seats in the parliament. The winner-take-all system, however, encourages compromise. Instead of having their own candidate run for elections, many smaller parties support the Republican or Democratic candidate who more closely represents their views.

James Reichley, author of the book The Life of the Parties, says a multi-party system is not suitable for a diverse country like the United States and it often does not work in small homogeneous countries: ?The Italians have had a hard time since the Second World War in putting together coalitions. At times the French also. It creates a more unstable situation. And those are relatively small countries. I think in a country like the United States, the two-party system works well. There are some people who don?t agree with that.?

James Reichley says the major parties are trying to reach the average voter so their platforms are not radically different. But they are distinctive enough to motivate their core supporters. Furthermore, according to Mr. Reichley, the two-party system is more transparent because coalitions are formed before elections. It also allows major parties to disregard uncommon or undesirable ideas, such as extremism and racism.

But critics argue that this system is unfair because it often weeds out good causes. Furthermore, in an effort to attract voters, Republicans and Democrats adopt each other?s popular issues, so that the difference between them is not as pronounced as the differences among political parties in other democracies.

What often provokes the most criticism is the power of the two major parties. Political scientist Bruce Larson says they have used their power to prevent third parties from participating in elections: ?To get elected, you have to get on the ballot and who gets on the ballot is decided by laws in each state. State ballot-access laws thwart minor parties. They make it difficult for minor parties. The two major parties have passed laws in most states that give them automatic access to the ballots. So Democratic and Republican candidates automatically get put on the ballot in general elections in every state.?

To run in an election, a member of a major party needs only one signature, says Professor Larson, while a small-party candidate has to collect thousands of signatures from supporters to get on the ballot.

Furthermore, notes Jamin Raskin, professor of constitutional law at American University here in Washington, in presidential elections, for example, the two major parties automatically get government funds to pay for their campaigns, a privilege not easily won by smaller parties: ?The minor parties are not eligible to get that money unless they get five percent of the vote in the election,? says Professor raskin. ?And if they get five percent of the vote in the election, then they will get money retroactively. But they don?t get any money up front. And if they don?t reach five percent, they don?t get anything.?

Professor Raskin says small parties rarely can afford the cost of running a campaign. But he adds, even if they can?t run, third parties do have an influence on American politics: ?Third parties have been behind not just the abolition of slavery, but the progressive income tax, woman suffrage, child labor laws, the right to organize a union, and so on, and so third parties have played a very important role even when they haven?t won.?

How is that possible? Because major parties often adopt minor-party issues that matter to their constituents in order to win votes.

Most analysts say that despite imperfections, America?s two-party system has served the nation relatively well for most of its history. And it?s a system that is not likely to change in the foreseeable future.