top of page
  • Writer's pictureCapture Politics

Lib-Dem/Labour electoral pact, would it work?

This blog discusses if a progressive alliance would work

Some Statistics

“According to the results of the last election, there was a potential of 44 constituencies the Lib-Dems could gain from the Tories. However, there are only around 13 seats that would have the potential to be gained by the Lib-Dems if all 2019 Labour voters instead had backed the Lib-Dems in the event of an electoral pact being formed”

Due to the nature of #FirstPastThePost (FPTP), where the winner takes all, there have often been many intense debates amongst local party representatives over the question of forming pacts with similarly ideological opponent parties. The rise of #TacticalVoting sites reflects the increase in such debates taking place within politically interested circles. In the last #election, the #BrexitParty unofficially formed a pact with the #ConservativeParty to bolster the chances of a majority #ProBrexit government being formed. Moreover, there were campaigns that focused on forming a #Remain based #coalition leading up to the #2019Election. Although such campaigns failed this does show there is much talk on creating electoral pacts in order to overcome the strategy problems FPTP has brought to progressive parties. However, this does present the question of "Do such #ElectoralPacts work?" For example, would a #LiberalDemocrat and #Labour pact help a progressive alliance win a majority, or even become the largest party? To test this question we analyse how an electoral pact could have helped Labour and the Lib-Dems in the last election.

Labour targets under a Lib-Dem pact:


Traditional Key marginal seats: Table 1.

Note: The above table column outlines the % of the #constituency that voted to leave (col2), then it states if the area voted to leave, or not, followed by the constituency's name and its regional location. 19Maj shows the majority level for the winning party, the next two columns show when Labour last won the seat with its respective majority. The next two columns show the Labour and Lib-Dem Party 2019 % share of the vote. The last columns display if an electoral pact would work or not based on the % of Lib-Dem votes that could be successfully transferred to Labour (using 2019 stats as an example). This is the same for all the tables in the blog post.


One argument that could be made is that Labour could be helped through an electoral pact where the Lib-Dems would stand aside in Labour-Conservative battleground seats. There are 54 of these seats in which Labour could still realistically win which #NewLabour won. Out of these 54 seats in the last if the Lib-Dems had stepped down, and instructed all their voters to back Labour (and this happened), then Labour would have won 11 of these 54 target seats, which would have diminished the Tories majority to 69. However, it is unlikely that all Lib-Dem voters would back Labour in this scenario, with some possibly preferring to back the Conservatives over Labour, if they were in such a way forced to choose. If just 10% of these 2019 Lib-Dem voters swayed to the Conservatives (with the other 90% backing Labour) this would reduce the number of seats Labour would have won to just 8, and 6 if there was an 80/20 split. Therefore, the impact of a #ProgressiveDeal seems limited within these groups of seats. The good news for Labour here would be that as their base has become more Remain and #liberal inclined a high transfer of Lib-Dem to Labour voters could be possible, so it is likely Labour would gain 5-10 seats in the above scenario. Yet, it should be noted that this only would have brought the #Tories’ majority down to around 75-70 seats and this is not the winning coalition some might argue it to be.

New Labour-Tory marginal (15). Table 2.

Focusing on the seats which have displayed narrowing Conservative majorities, and are now battleground areas between Labour and the Conservatives, if the Lib-Dems had stood down in these seats and strongly encouraged their voters to back Labour (and all did so) then Labour would have gained a further 9 seats. Yet, again a full transfer of votes is unlikely so around 7-8 seats are the most likely amount of gains. Again, a high transfer of votes is likely as these areas most strongly voted to Remain, and therefore the many Lib-Dem Remain votes likely would have gone Labour’s way. This would have reduced the Tories’ majority by 16 based on the current seats looked at.

Red Wall seats (30): Table 3.

Looking at the seats Labour had held for a long-time and lost in 2019, if there was a 100% transfer of the Lib-Dem vote to Labour this would have only stopped the Conservatives from gaining 13 out of these 42 seats. However, these are mostly leave backing areas and if these voters were forced to choose between Labour and the Conservatives it might be possible that a noticeable number of Lib-Dem votes would transfer to the Tories instead. This brings a Labour Lib-Dem pact to the most likely total of potential gains to 10 out of 42 seats. When considering the other seats mentioned earlier this means a Labour Lib-Dem pact in the last election would have gained 20-25 seats, bringing down the Tories majority to at best 55.

Old Labour seats (12): - Table 4.

Another thing that needs to be taken into account is the effect a Labour Lib-Dem electoral pact could have on key-marginal seats that are battlegrounds between the Liberal Democrats and the Conservatives. According to the results of the last election, there was a potential of 44 constituencies the Lib-Dems could gain from the Tories. However, there are only around 13 seats that would have the potential to be gained by the Lib-Dems if all 2019 Labour voters instead had backed the Lib-Dems in the event of an electoral pact being formed. Yet, it must be stated that the Lib-Dems would unlikely to have a 100% direct transfer of Labour voters. Let us say for example that 90% of Labour votes went to the Lib-Dems, but 10% went towards the Conservatives. This would reduce the number of seats that could be taken off the Tories to 11, and if an 80-20 split scenario occurred then this would reduce the amount of gained seats to only 8. If the Lib-Dems only gained 60% of these former Labour voters, and most of them decided to vote Conservative instead, then this would only help the Lib-Dems win two seats.

Table 5 - Estimation of Lib-Lab pact gains based on a 60-100% success ratio.

Overall, in these remain, younger, more highly-educated seats many more Labour voters are compatible with the Lib-Dems than they are the Conservatives. In fact, some many votes Labour lost in the last election did go to the Lib-Dems, so a bad outcome of a 60 (Lib-Dem) – 40 (Conservative) split of Labour 2019 voters in these #MarginalSeats is not the most likely option. At first glance, a Labour-Lib-Dem electoral pact appears most likely to only take in the region of 5-10 seats off the Conservatives and being gained by the Lib-Dems. Consequently, it could be said that the best way for the Lib-Dems to win seats off the Conservatives is not focusing on electoral pacts, but rather pursuing a revival of their polling fortunes. This revival would need to come from 2019 Conservatives voters, a hard thing as most of these voters voted to leave the EU and have grown ever more distant to the Lib-Dems since their 2005-2010 high-watermark period due to differences on issues like migration, the EU and their time in the coalition government. Therefore, the best option might be to merge the Lib-Dems into Labour and fight as one party on one ticket.

Table 6 - Lib-Dems wins under pact

Moreover, it is important to remember that many of the Lib-Dem top target seats are not a straight forward gain for the Liberal Democrats, even with the help of a Labour/Lib-Dem electoral pact. If the parties made a pact in 2019 in these Lib-Dem target seats that voted to leave the EU then there are only two seats that would change hands based on a 100% Labour to Lib-Dem vote transference. This goes down to one when only a few Labour voters chose to vote for the Conservatives over the Lib-Dems, which could have easily occurred with Labour #LeaveVoters. Moreover, Labour voters are increasingly a Remain base of voters, meaning that in these leave seats the Lib-Dems might struggle to pick up enough Labour voters to win these seats, even with an electoral pact being made. This goes to show just how difficult it is for the Lib-Dems to stage a comeback in these seats and that a revival of Lib-Dem support is more needed than an electoral pact for the Lib-Dems to be able to win more of their battles with the Conservative Party.

Lib-Dem – Tory Marginals (Remain seats).

The biggest impact a Labour-Lib_Dem electoral pact could have is in the Lib-Dem’s remain voting target seats. There are 26 targets of this type and 11 could be gained if all Labour voters had backed the Lib-Dems in 2019. As said earlier it is unlikely that all Labour voters would have chosen to vote Lib-Dem over the Conservatives, so if 90% of Labour voters would have voted the way the pact wanted them to 10 seats would be gained, and if the Lib-Dems only gained 80% of these voters this goes down to 6 to 7 seats gained. The pact here likely would get a strong Labour to Lib-Dem transference due to the compatibility of Remain Labour voters being high in numbers in these constituencies, moreover, the average demographics in these seats strongly favours Labour over the Tories. However, even if the pact worked as intended only around 10 seats could have been gained from the Tories in favour of a progressive alliance. Therefore, an electoral pact would have some impact on the Conservative’s ability to form a majority government, but it might not be as big as first thought. When taking into account how it might also help Labour win Tory-Labour marginal seats these gains go up to 35, not enough to eliminate the Tories majority, but in a closer election it could help Labour become the largest party, and possibly allow a Labour-Lib-Dem coalition government. However, for this to be possible the pact would have to distribute votes as intended and also the rest of England & Wales would have to be split fairly evenly between Labour and the Tories.


Overall, a Lib-Dem-Labour pact would not have stopped the Conservatives from winning a majority, nor weakened the government’s majority enough to give the opposition some power in this parliament. The best possible scenario of this pact could bring the Lib-Dems and Labour only 35 of over 100 target seats. Although a low figure such seats could be crucial in a hung parliament scenario where Labour only beats the Conservatives by a few points and is just about the largest party. This could be very useful for Labour as it could help them avoid the nightmare hung parliament scenario where the SNP would be the only party that held the balance of power. This would be beneficial to avoid as the difficult SNP power-broker scenario probably hurt Labour’s governing credibility in the 2015 election. However, unlikely as this scenario is compared to other outcomes if it were to occur the pact would need to transfer votes the way intended, which might not always be the case. In fact, this will be hard to achieve in some cases as the Lib-Dems mostly gained through the Labour’s demise in 2019 and the large Leave voter base the Tories have in some target seats won’t be an easy gain for the Lib-Dems, or Labour, as some of their former Leave voters have been growing ever more distant from these parties for several elections. The pact could work in predominately Remain-voting areas where the demographics and politics of the constituency would likely vote accordingly to how a Lib_Dem-Labour pact would want them to, yet there are only a small number of such seats. Therefore, overall such a pact might be hard to make work as some voters will not vote as the pact would like them to. Perhaps a much better option would be for the Lib-Dems could to go it alone and target Conservative voters, as hard as this will be, in order to rebuild their vote share without hurting their only potential ally of Labour. Alternatively, perhaps the most effective solution would be for the Lib-Dems and Labour to merge into one progressive unionist party which could much more effectively target and hold together these different groups of voters that are voting for very similar things but are splitting their vote across different parties. In an FPTP system perhaps this is the best viable strategy for progressive unionist parties to succeed given how the country has been split by Brexit.

Related Posts

See All


bottom of page