-- by David Swink, FCTA, 08/28/2016
Unlike in parliamentary systems, third party candidates in the United States don't play well in our two-party system of government -- often acting as spoilers and flipping the general election to the consternation of those same voters silly enough to effectively promote their last choice to public office.
Parliamentary systems typically will have two major political parties that dominate in the popular vote -- usually a left-wing party and a more moderate or slightly right-of-center party. But there are usually a number of smaller parties of various flavors or based on narrow issues. Representatives in the parliament are allocated proportional to their popular vote.
In parliamentary systems, the country's leader (Prime Minister or President) is selected by a majority vote of the members of parliament. If no party achieves a majority in the popular vote, the various parties will have to negotiate between themselves, and two or more parties will agree to form a "coalition" to achieve majority status in the lower house of parliament and select the nation's leader.
To put this in a U.S. context, you would select your local congressman (not necessarily limited to two parties), and the majority party (or a coalition of two or more parties) would select our president and vice president. There would be no separate presidential election by the people.
There are variations within parliamentary systems around the world including runoffs for major leadership positions, but mostly all require a majority rather than a mere plurality vote.
The U.S. System
In the United States, we vote for our legislators and presidential candidates separately, with rules generally determined by each state. And most states require only a plurality to obtain public office. For example, here in Virginia, the last gubernatorial and the last U.S. senate race were three-party races each won by a narrow plurality -- the Libertarian candidate drew enough of the vote that might otherwise have led to a Republican victory.
For presidential elections, the U.S. Constitution requires direct popular votes within the states, moderated by an "Electoral College" system. Each state is allocated delegates equal in number to the state's U.S. Congressmen and the state's two U.S. Senators. (Currently in Virginia, 11+2=13.) Traditionally, each state awards their entire delegate vote to the winner of that state's popular vote -- a winner-take-all approach. Only two states (Maine and Nebraska) don't follow this protocol.
Note that the Electoral College system pretty much guarantees a two-party outcome, as only rarely would a third-party candidate be able to capture the Electoral vote of any state. (George Wallace carried five states and 45 Electoral votes in 1968, drawing votes from Hubert Humphrey and giving Richard Nixon the election.)
Why NOT to vote 3rd-party
Under the current U.S. "plurality-is-enough-to-win" election system, voting for a third-party candidate may make you feel good, but will most likely benefit that major-party candidate whom you most despise. Like it or not, you really need to vote for the "lesser of two evils".
How to "fix" this
Until we collectively require a popular majority in order to win an election, we're stuck with voting for the "lesser of two evils". And since we're not likely to amend the Constitution on this issue, the only alternative is to adopt a "two-round" or runoff system. Certain states (eg - Louisiana and Georgia) have already implemented this -- at least for non-presidential elections.
There are two types of runoffs: separate-election and so-called "instant" runoffs. A separate-election runoff is just that -- perhaps two weeks after the initial election where no majority was attained. But since a second round of elections is expensive, some have opted for the "instant" runoff.
On ballots with instant runoff requirements, you vote for your first choice, second choice, etc. And if no candidate has more than half of those votes, then the candidate with the fewest first choices is eliminated. Voters who selected the defeated candidate as a first choice then have their votes added to the totals of their next choice. This process continues until a candidate has more than half of the active votes or only two candidates remain. The candidate with a majority among the active candidates is declared the winner. (Ref: Watchdog.org.)
More states could individually choose to implement a runoff system of some sort. And since the Constitution does not prohibit the runoff concept, a federal law could even be implemented to require this nationwide -- at least in national elections.