By "power erosion" I refer to the phenomenon which usually affects a party in power: the trust gets lower towards the end of the legal mandate, thus reducing the chances of wining the power for the next mandate.

In my native country, Romania, a much more fragile democracy (only 27 years after the fall of the Communism and a few years before WW2), I have seen several important political parties suffering from "power erosion":

  • National Peasants' Party is almost 100 years old and failed to enter Parliament (5% electoral threshold) for three times in a row (the latest)
  • National Liberal Party, more than 100 years old and one the most notorious parties in country's history got only 20% of total votes at the last elections and some analysts argue that they might get lower in lack of solutions
  • Other smaller parties disappeared from the Parliament after 2-3 mandates

This article shows the evolution of public trust in Government:

The public’s trust in the federal government continues to be at historically low levels. Only 19% of Americans today say they can trust the government in Washington to do what is right “just about always” (3%) or “most of the time” (16%).

This article confirms the historical low trust level:

Public trust of government is near its all-time low according to the Pew Research Center, which finds a perfect storm of factors -- including a deep recession, high unemployment and polarized Congress -- are driving distrust near an all-time high of 80%.

At the same time, this table shows that the two main parties act and acted as a "political oligopoly" for many years.

Question: considering the low levels of public trust, how comes that there is virtually no political alternative to the two parties?

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    If you go back far enough (150+ years), the United States used to have the Whigs and Federalists parties, which are now long gone. Further, our current parties have undergone major position shifts over the last 150+ years. Commented Apr 14, 2017 at 0:08
  • I'm not sure about Romania political system but comparing with Polish you can blame winner-takes-all and electoral college. In current US system the 3rd party candidates are often symbolic and them gaining power risk weakening closest candidate splitting their votes. In Polish (for president) the winner of first round is paired against the second place if (s)he doesn't have majority. So with that system people could vote for, for example, Stein without fear of making Clinton position weakened (assuming potential Stein voted for Clinton). Commented Apr 14, 2017 at 2:09
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    @MaciejPiechotka - yes, Romania (and possibly many European countries) have similar electoral systems to Polish one. A recent example showed what I see it is major advantage of this system. A small and young party formed mainly from people from private companies and scientists managed to become the second political force within the capital city (Bucharest). They also managed to become the third force within the Parliament (some 9% of total seats). It sounds small, but this ensures a place in all TV debates (there is some law that forces media to allow a balanced representation in debates).
    – Alexei
    Commented Apr 14, 2017 at 8:29
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    @T.E.D. It is erosion of one party but a 2 party system is in itself relatively stable. Compare it with Polish parliament which contains 6 parties out of which only 3 existed during last election. If we go back to 1997 election only 1 existed. Commented Apr 14, 2017 at 22:23
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    Although the two parties exist under the same name since a long time ago, their ideologies do change. For example, the Democrats are now often crusading for minority rights, but in the 19th century they were more conservative than the Republicans, and were pro-slavery. So parties do change, even in America, maybe not as fast as in other countries.
    – vsz
    Commented Apr 17, 2017 at 10:46

5 Answers 5


There are probably a dozen correct answers to your question. The reasons for it contribute and pile on each other. I have no way of telling which reason is the most important.

As you pointed out, American trust in our political leaders is at an all time low. As a sign of this the Republican party elected a President who is not a politician, Donald Trump. The Democratic party had a serious primary challenger who was not a Democrat, Bernie Sanders. Both of these people were able to gain political traction despite not being part of the party establishment, because American trust in our political parties is so low.

Both of these candidates ran as a party candidate, despite having no real affiliation to that party or support from the party power structure. The alternative to this is to start a third party.

President Theodore Roosevelt ran for a third reelection as a third party candidate in the 1912 presidential election. The election was very weird by American standards. 4 candidates got a large share of the vote. The winner, Woodrow Wilson, got 40% of the popular vote and won 81% of the electoral college.

Taft was the third place candidate. Roosevelt and Taft agreed on a lot of issues. If one of them had dropped out of the race, the other would have had a much better chance of winning. The actual outcome was a landslide loss for their ideals. Roosevelt's new party fizzled out over the next few election cycles.

This outcome is baked in to our electoral system. Although the political landscape has changed a lot in the past 100 years, the election system has not. Simply put, the American election system strongly discourages the existence of a third party. You get more political traction if you work within an existing party to change the course of that party. If you start a third party, you may wind up sabotaging the main party that you are politically closest to.

Wikipedia has a pretty decent write up of this. Duverger's law is also very relevant.

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    Thanks for the quick and good answer. This explains it very well, but I am wondering how is it possible to have only two parties within a modern society. Things are so diverse and complex there days, that I doubt only two parties can catch this diversity. The list of parties in Netherlands shows an interesting political power distribution.
    – Alexei
    Commented Apr 14, 2017 at 8:42
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    One of the other things that currently hampers a 3rd party candidate that BobTheAverage didn't mention was that for most debates, a candidate needs to poll at least 10% to be allowed on stage. That's not a hard rule in the primaries (I think the Republicans had 14 candidates trying to get into a 12 person circus during the 2016 primaries), but I've heard it several times for the final candidate's debates.
    – krillgar
    Commented Apr 14, 2017 at 10:57
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    Look into Duverger's law too. @Alexei Commented Apr 14, 2017 at 15:31
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    @Alexei It's true that two parties can't cover much diversity, but the issue is that a party, by necessity, must hold a position on every single policy matter out there. And people in the United States at least tend to care most about a few specific policies. Regardless of what a party's stance might be on 95% of its issues, if it's in line with John Smith's views on the two or three major ones, then he's likely going to vote for that party's candidate. It's only after the election that voters see the other 95% of those policy/issue stances in action and find they don't like them.
    – TylerH
    Commented Apr 14, 2017 at 15:41
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    @Krillgar That is one of the dozen reasons I mentioned in the intro sentence. Commented Apr 14, 2017 at 16:12

You seem to be asking three questions:

1. Do parties in power suffer from power erosion

Actually, they do. During 20th century, Democrats went from near-collapse in early years, to post-depression having control of Presidency and both Congress branches; then they suffered setbacks that led to 12 years of R presidency post-Carter; they had control of Presidency and both Congress Branches under Clinton again till they lost Congress in 1994. Then they retook all branches again briefly in 2008; only to lose them all between 2010 and 2016.

Much of this shift happened for fundamental reasons - but much was also attributable to voters getting upset with the party in power recently.

The difference is that in the USA, the power erosion simply moves the balance between two main parties, usually.

2. Why does no third party alternative arise?

Actually, it does. Just not all that frequently.

  • Federalist party disappeared at the end of First Party system, with Democrat-Republicans fracturing

  • Whigs lost power in 1850s at the end of Second Party system, replaced by Republican party.

Additionally, there were cases where 3rd party didn't arise but one of the 2 big parties dominated completely:

  • Under the 3rd Party system, Democrats lost much power, as a result of Civil War and Reconstruction. That continued for most part into Fourth Party system as well.

  • As mentioned above, during Fifth Party system, New Deal resulted in complete reversal, with Democrats gaining most power and Republicans in shambles power wise.

Additionally, there were notable 3rd party challenges, at least as far as popular vote.

  • Theodore Roosevelt's second Presidency

  • Ross Perot's run

  • 21st century saw pretty big rise of "independent" voters, although that never translated into emergence of 3rd party (see below for why)

3. So, why don't 3rd parties arise more frequently?

This was covered exaustively elsewhere on this site, e.g. " Does the USA have more than 2 political parties (Democrat, Republican)? " - in short, Duverger's law states that this is an expected outcome of US's First-Past-The-Post electoral system.

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    You might argue that today's Republican Party is the Tea Party that assumed the Republican name. They could never have won under their own party name so they subverted the Republican party.
    – wilsotc
    Commented Apr 13, 2017 at 19:09
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    @wilsotc - That's ... not anywhere near accurate.
    – user4012
    Commented Apr 13, 2017 at 19:23
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    Duverger's Law plus a lot of procedural burdens designed to preserve the system. Commented Apr 13, 2017 at 23:30
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    @wilsotc The 'Tea Party' was never really a party to begin with. It was always a wing of the Republican Party. Also, while subverting the GOP could possibly be argued for getting Trump nominated, the vast majority of GOP members of Congress have been there since before the Tea Party movement even existed and are neither part of it nor were particularly even fond of it.
    – reirab
    Commented Apr 16, 2017 at 6:09
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    When the former Republican president and much of his family public announces they're not voting for the Republican nominee for president that indicates major changes to the party. No the congress hasn't changed much but former power in the senate McCain/Ryan are falling into line with the new leadership. McCain called the nuclear option stupid right before he voted for it. If not subverted, they took a huge first step away from Republican ideals. Think Ronald Reagan would be for eliminating all social programs? Social security, Medicaid? Reagan expanded Medicaid at least 3 times.
    – wilsotc
    Commented Apr 17, 2017 at 13:13

The political system in the US (and to a slightly smaller degree the UK) is essentially rigged to only allow 2 parties to dominate. This is through a combination of things like First Past the Post electoral systems and gerrymandering.

Here's a very simple example - lets say you have two parties. Lets call them L and R.

Now you create a third party, we'll call it C. You run a hugely successful campaign, get massive popular support. I'll use the UK terms here since I'm more familiar with them so lets say you manage to find an MP to stand in every constituency. You manage to find the deposit for those MPs.

Then the results come in (note these are exagerated to illustrate the point, differences this severe are unlikely) -

  • Constituency 1: 1% L, 40% C, 59% R. -> R gets an MP
  • Constituency 2: 73% L, 15% C, 12% R. -> L gets an MP
  • Constituency 3: 31% L, 21% C, 48% R. -> R gets an MP
  • Constituency 4: 30% L, 31% C, 39% R. -> R gets an MP
  • Constituency 5: 57% L, 40% C, 3% R. -> L gets an MP

You end up with a parliament consisting of 3 MPs for R, 2 MPs for L. None for C.

Despite the fact that you got second place in all but one constituency you ended up with no representation at all in parliament. What's more for anyone in constituency 1, 2, 3 and 5 - their vote is utterly meaningless.

1 and 3 will basically always return R. 2 and 5 will always return L. Anyone voting for anything in those constituencies is achieving nothing.

In fact what's even worse - if you hated R and lived in 3 then you are in a tough place. You might passionately believe in C. You think they are awesome and you really want them to be elected. But the vote between L and C is now split. 52% of the people in 3 may want "anything but R" but (because their vote is split between L and C) R walks in anyway. So do you vote for L just to keep R out? (That's called tactical voting).

So the end result of all of this is "Swing" constituencies, in this case 4. The people there actually sway the result of the entire election. Whats more there is a lot of inertia there. Lets say 25% of the voters there will always vote for their preferred party. 25% C, 25% L, 25%R. The remaining 25% are the only people in this entire system who have a vote that counts.

So of the original 5 constituencies the result of 20% actually sways the election - the Swing Constituency. Of those 20% in that constituency only 25% actually change their vote ever - the Swing voters.

So the entire election result is decided in this simplified example by 5% of the voters. This is why campaigning and funding and suchlike is always focused on these areas and those voters.

Everyone else has no say.

The system is broken. But unfortunately it favours those who are already in power by making sure they stay in power - so it is highly unlikely to change.


Because the United States has a first-past-the-post presidential system, while Romania has a multiround parliamentary system, which was designed partially to avoid the pitfalls of the presidential system. The difference you describe is generally regarded as the primary downfall of a presidential system (there are downfalls of parliamentary systems too, but you didn't ask about those, so I won't address them.)

In the US congressional elections, each person gets exactly one vote. Whoever has the most votes wins, even if that isn't a majority of votes. For example, if everyone in the US voted for themselves for Congress, except for one person who voted for his neighbor, then his neighbor would have two votes, so he would win.

Because of this, voting for someone who is not popular almost guarantees that your preferred candidate will not win. So people instead choose to pick from the two most popular candidates, so that the one they dislike more will lose. For example they may vote Democrat so that the Republican will lose, rather than because they like the Democrat.

The end result of this is that people will vote for a Democrat or Republican because they believe that their vote will be wasted on a third party candidate.

There is a lot of complexity in this issue, but that is a major component of it.

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    The president has to get a majority of electoral college votes to be elected. I was unaware that congressional elections don't require a majority. That's very surprising. You have some kind of citation for that information?
    – DCShannon
    Commented Apr 13, 2017 at 23:48
  • @DCShannon "congressional elections don't require a majority" What is surprising about the person with the most votes winning, a plurality, but not a majority ? Commented Apr 14, 2017 at 14:51
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    Here is a source. It points out that there are several states which require a majority of votes cast, but they are a minority. Question 6 is the relevant one. clerk.house.gov/member_info/memberfaq.aspx EDIT: It doesnt address Senatorial elections but the circumstances are similar. Commented Apr 14, 2017 at 16:09
  • @DCShannon You're right that the President has to get a majority of electoral votes to win. However, unfortunately, the problem described here still applies to the Presidency because almost every state allocates all of its electoral votes to whoever wins a plurality of the popular vote in that state (which is totally absurd.) So, currently, if there are 5,000,000 votes for candidate A and 5,000,001 for candidate B, candidate B gets all of the electors for that state. The only exceptions are Maine and Nebraska, both of which have only 3 or 4 electoral votes anyway.
    – reirab
    Commented Apr 16, 2017 at 6:17
  • @DCShannon As a result, you still have the issue of voting for candidate C instead of A or B potentially causing the one you like least to win. For example, in Utah during this past election, both Gary Johnson and Evan McMullin were polling quite high (20+%) at various times. Even though Clinton was probably the least favorite candidate of 70% or more of voters in that state, she had an outside chance of winning it due to the votes against her being split. In the end, Trump ended up winning it, though.
    – reirab
    Commented Apr 16, 2017 at 6:25

Auatralia provides an interesting example at the Federal (national) level. There are two main parties (one of which is technically a coalition), which between them have dominated the political system since World War II. Several minor parties have come and gone in this period; at the moment the Greens is the strongest minor party.

There are two Houses of Parliament. The House of Representatives, which is fairly similar to the British House of Representatives and which is where the Government is decided, has single-member electorates, but the voting is by preferential voting. If there are four candidates in my electorate I order them 1, 2, 3, 4 according to my preference. If my number 1 candidate gets few votes, he or she is eliminated, and my vote passes to my second choice, and possibly to my third choice. This allows me to put a minor party candidate first, but to give my second preference to the major party that I prefer. This should allow a minor party that is growing in popularity to steal votes from a major party and eventually to replace it, but that hasn't happened: at least since World War II the two major parties have held between them 95% of the seats or more.

The upper house, the Senate, has proportional representation, each State forming a single multi-member electorate. This has given minor parties and single-issue candidates a chance to be elected, and at present minor parties and independent candidates have over a quarter of the seats, an all-time high. The Government is forced to negotiate with some of these groups to get anything passed in the upper house.

Thus at present Australia appears to exemplify both parts of Duverger's law.

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