Explainer: how do minority governments survive?

Most experts are now predicting another hung parliament after the 2015 election – so attention is switching to the type of government that is likely to emerge. The hung parliament of 2010 produced a Conservative-Liberal Democrat coalition but after the Lib Dems’ unhappy experience in office – and with neither Labour nor the Conservatives prepared to form a coalition with the resurgent SNP – the UK may be heading for a minority government.

This is where one party doesn’t win enough seats to secure an overall majority. It forms a government and seeks to negotiate support from other parties for each individual vote in parliament, although it might obtain a “confidence and supply” arrangement – a guarantee of support for its budget and in no-confidence votes.

There is some fear that such an arrangement would be unstable. A minority government would constantly have to cobble together majorities for each vote, making the process of governing difficult. Small opposition parties might seek to hold the government to ransom, threatening to bring it down unless it offered policy concessions. They may regard such behaviour as legitimate if they view the minority government as having only a weak mandate from the electorate.

But minority administrations are common in Europe. They are currently to be found in Sweden, Denmark and Norway. Many survive a full term in office and secure important achievements for their country.

It’s not beyond the realms of possibility, therefore, that minority government could survive in the UK and even do a good job.

The power of the median

To understand how a minority government would work in the UK, it is helpful to consider one of the most important concepts in political-science analyses of multi-party systems: the so-called median legislator.

The theory of the median legislator assumes that what matters in a parliament is not just how many seats each party has but where those seats are ideologically positioned relative to each other. Research in the 1990s found that 80% of minority governments in Europe since 1945 either contained or were supported by the party with the median legislator.

Imagine that all the legislators, or MPs, in a parliament were lined up in order from the most left-wing to the most right-wing. The median MP is the middle one in the line. If there were nine MPs, the median would be number five. This MP would have the same number of MPs on either side of them on the ideological scale. For simplicity, we can assume that MPs in one party will follow each other sequentially in the ranking – so all the Labour MPs follow each other, with no Lib Dems interspersed between them, for example.

The power of the median can be seen by considering the example in Figure 1. Four parties, A, B, C and D, are spread along the left-right ideological spectrum. The number of seats they hold is indicated in brackets, with the total numbering 99.

Author provided

The median MP is thus the 50th, counting in from either the extreme left or the extreme right. This MP belongs to Party C.

Counting from the left, parties A and B have 45 seats between them – five short of the 50th MP. On the right, party D has 40 MPs – ten short of the 50th.

Neither side has enough seats to form a majority, making party C the king-maker. It could form a coalition with either party D or parties A and B. Party C’s preferences could determine the legislative proposals of the government, as it can play off left against right for maximum leverage, despite the fact that it is the smallest party.

This applies not only to coalitions but also to minority administrations. What matters for a minority government is ensuring the other parties don’t vote down proposals.

If party C ran a minority government, any attempt by D to pull policy to the right would be opposed by A, B and C. Similarly, an attempt by A or B to shift policy to the left would be prevented by C and D.

Election 2015

This type of analysis can be applied to the forthcoming UK election. In the House of Commons, there are 650 MPs but one is the Speaker, leaving 649.

The median MP is thus the 325th in the ideological ranking (I ignore here Sinn Fein’s abstentionist policy towards the Westminster parliament).

Figure 2 shows a rough left-right ranking of the UK parties, based on a recent prediction of the number of seats each party will have after May 7. Author provided

The Greens and Sinn Fein are furthest to the left; the SNP and Plaid Cymru occupy the same position to the left of Labour; the SDLP adopts the same position as Labour (its MPs informally take the Labour whip in the House of Commons); the Alliance Party of Northern Ireland adopts the same position as its sister party, the Liberal Democrats; the Conservatives are on the centre-right, followed by the DUP and the independent Unionist MP, with UKIP furthest right.

Some might argue the DUP is to the left of the Tories and it has left open the prospect of a deal with either main party. However, I assume an agreement with the staunchly unionist Conservatives is more likely and so place it to the right.

A Labour minority

On these figures, the 325th MP, counting in from left or right, will represent Labour, but only just: a four-seat swing from Labour (or the SNP) to the Lib Dems, Conservatives or UKIP would give the median parliamentary seat to the Liberal Democrats.

Having the median MP should give Labour considerable bargaining power in a hung parliament. Ed Miliband has said Labour would not form a coalition with the SNP, although he has left open the prospect of a confidence-and-supply agreement, or a minority coalition with the Liberal Democrats.

However, if Labour could rely on the SNP not to join forces with the parties of the right, it would be in a strong position to pass many of its manifesto policies. That might require occasional compromises with the SNP (particularly on Scottish matters) and the Lib Dems, but a minority Labour administration could be stable. It could rely on the parties to its left to support its policies on public services and welfare against opposition from the right-wing parties.

A minority Labour government would also be feasible if the Liberal Democrats emerged as the party of the median MP, provided that the latter abandoned their current alliance with the Conservatives in favour of one with Labour.

A Conservative minority

For the Conservatives to control the median MP, their seat tally – added to those won by UKIP and the unionists – would need to total at least 325.

A minority Conservative administration governing from the right – the preferred option of many Tory backbenchers – would therefore require more MPs than is currently being predicted.

It might be possible to form a minority government that was not backed by the party of the median MP but it would most likely be highly unstable. It could be defeated if the parties of the left and the Liberal Democrats joined forces to oppose it in a confidence vote. Indeed, former SNP leader Alex Salmond has said the party would block a Conservative minority government altogether.

Author provided

Figure 3 shows an alternative allocation of seats that would give the Conservatives the median MP. In this instance, a minority Tory government would be feasible and it could govern either from the right or the centre-right.

The right-wing option would see it rely on the votes of UKIP and the unionists – perhaps offering concessions on the EU referendum and public spending in Northern Ireland. The centre-right option would entail another agreement with the Liberal Democrats, whether a formal coalition or, more likely, a confidence-and-supply arrangement.

Unless the Conservatives substantially improve their predicted seat gains between now and polling day, it seems that the best opportunity for a minority Conservative government would be through the support of the Liberal Democrats as the party of the median MP – just as they were after the 2010 election. That might require the Lib Dems performing better than they are currently predicted to do, particularly in those seats where they face a challenge from Labour or the SNP.

The Tory right would probably continue to face blocking opposition from the Lib Dems on what they see as traditional Conservative policies. The pull to the centre could only be weakened if the Conservatives, UKIP and the DUP won a combined minimum of 325 seats.

Minority governments can be stable as long as they enjoy the support of the party of the median MP. A strong surge is required before that could apply to the Conservatives. Maintaining current performance is required for it to apply to Labour, although it would need to be wary of the SNP causing it problems in government.

What we have learnt about the power of the median, though, is that it is just possible that the Lib Dems – battered and diminished in numbers – could still find themselves as the king-makers in May, just like in 2010.

Tom Quinn does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.