While political parties in the United States other than the Democratic and Republican have fielded presidential candidates for years, they have never won the White House. VOA's Jeffrey Young explores how these third party candidates have nonetheless influenced the outcome of elections.

In 1992, Democratic Party presidential candidate Bill Clinton defeated the incumbent Republican President George H.W. Bush, the father of President George W. Bush, by nearly six million votes. But a so-called third party candidate, Ross Perot, received almost 20 million votes.  Many political observers say the votes cast for Perot clearly affected the outcome of the contest between Mr. Bush and Mr.Clinton.

The United States has two major political parties, the Democratic and the Republican. But there are others, such as the Green Party, the Libertarian Party, and the Socialist Party.  These and other third parties have never succeeded in winning the White House.  The reason for that is the structure of the Electoral College that actually selects the president.

Benjamin Ginsberg at Johns Hopkins University in Washington D.C. says, "We don't actually have one national election.  We have 50 statewide [presidential] elections that are held on the same day.  And in each state, Electoral College votes are allocated, usually to the candidate that wins the most votes in that state."

Ralph Nader ran under the Green Party banner in 1996 and 2000 and also ran unaffiliated in 2004. He says the problem for third parties goes beyond the Electoral College. "The system does not encourage, because it doesn't have proportional representation [and] doesn't have instant-runoff voting. It does not encourage multi-party development.

While third party candidates may not win, they have been accused of being so-called spoilers.  That is how some pundits view Ralph Nader's 2000 White House bid.

The outcome of the 2000 presidential election ultimately hinged on the vote count in the southeastern state of Florida.  Republican George W. Bush won the state over his Democratic Party rival, Al Gore, by a margin of only 537 votes.  Mr. Bush's Florida victory enabled him to win the White House in the Electoral College even though Gore got more votes nationally.  Nader received more than 97,000 votes in Florida, sparking debates ever since as to what the outcome in Florida would have been if he were not on the ballot.

Some political observers say there is another reason why parties other than the Democratic and Republican do not win the White House and usually do not get seats in Congress.  Candice Nelson at American University in Washington, D.C. explains. "Their issues -- if they have resonance, if the American people are interested in them -- can get absorbed by one of the two major parties, which is why third parties don't have much staying power."

The next segment of "How America Elects" will focus on campaign fundraising, and the debate over whether the White House race should be entirely publicly financed.