the American Civil War (1861–1865), the major parties have been the Republican Party and the Democratic Party. Since 1860, six presidential candidates other than Republicans and Democrats have received over 10% of the popular vote, although one of them was a former president, Theodore Roosevelt. Third party In electoral politics, a third party is any party contending for votes that failed to outpoll either of its two strongest rivals (or, in the context of an impending election, is considered highly unlikely to do so). The distinction is particularly significant in two-party systems. In any case "third" is often used figuratively, as in "the third parties", where the intent, literally stated, is "the third and succeeding parties". The term "third parties" is used mostly in countries with first-past-the-post voting systems, as those systems tend to create a two-party system, so that successful smaller parties are rare. Countries using proportional representation give little advantage to the two largest parties, so they tend to elect many parties. Therefore, in those countries, three, four, or more political parties are usually elected to legislatures. In such parliamentary systems, coalitions often include smaller parties; since they may participate in a coalition government, there is not a sharp distinction with a 'major' party. In two-party systems, on the other hand, only the major parties have a serious chance of forming a government. Similarly, in presidential systems, third-party candidates are rarely elected president. In some categorizations, a party needs to have a certain level of success to be considered a third party. Smaller parties that win only a very small share of the vote and no seats in the legislature often are termed minor or fringe parties. Parliamentary two-party systems Third parties usually have little chance of forming a government or winning the position of head of government. Nevertheless, there are many reasons for third parties to compete. The opportunity of a national election means that attention will be paid to the positions of third parties. The larger parties might be forced to respond and adapt to their challenges, and often the larger parties copy ideas from them. Most third parties try to build their support to become one of the dominant parties, as the Labour Party in Britain and New Democratic Party in Canada did. In the Westminster system there is also the possibility of minority governments, which can give smaller parties strength disproportional to their support.