A progressive alliance is gradually creeping onto the agenda. Some kind of electoral pact between progressive parties (generally understand as Labour, Greens, Plaid Cymru, the SNP and the Lib Dems) has been proposed by the new leadership of the Green party, important figures in Labour and by a range of think tanks and media commentators. It's not hard to fathom why; without some kind of pact the Conservatives seem a dead cert to win the next general election. Even if Labour's current infighting ends, and its polling position recovers somewhat, the boundary changes that the Tories have pushed through make it far easier for them to win, as safe Labour seats are abolished in far greater number than safe Conservative ones. Labour tribalists dream of another 1997 style comeback in which it wins back hundreds of seats, but the idea of any party again receiving more than 40% of the vote seems implausible in our current era of multi-party politics.
Would a progressive alliance make much difference? Opponents of the idea argue that, for the Tories to be defeated, most seats need to move from Conservative to Labour, so the aim must be to persuade Conservative areas to switch sides. This is a category error - it looks at seats when it needs to look at votes. There are 37 constituencies in which the total Labour + Lib + Green + SNP/Plaid vote is higher than the Conservative majority (and several others which fall just below that line). That's 37 seats that the Conservatives wouldn't have won had a progressive alliance been in place in 2015, wiping out the Tory majority and putting Ed Miliband into Downing Street as the head of a centre-left coalition. A pact with just the Greens and Plaid would be insufficient - it would only have delivered another 13 seats. And in 2015 a pact between Labour and the SNP would have only delivered one extra seat, as only one Scottish constituency fell to the Tories (Dumfriesshire, Clydesdale and Tweeddale). This is however likely to be different at the next election, if the results of the Scottish Parliament elections are anything to go by, as in these the Conservatives won 7 constituency seats. The key point, though, is that to maximise its success, any progressive alliance must include the Liberal Democrats. 2015 was probably their nadir and they still attracted 2.4 million votes - there are seats (particularly in the South West) that have never been won by Labour, always by a Conservative or Liberal. Labour and Liberal activists will need to get over their tribal dislike of each other and start working together.
What would be the policies of such an alliance? It is, after all, meaningless to add up the votes of assorted opposition parties if there are few areas on which they agree. Fortunately, there is a lot of common ground. Under Corbyn, Labour is committed to overturning cuts and investing in public services and infrastructure - making their economic policy much more closely aligned with the Greens and SNP/Plaid Cymru. And whilst the Lib Dems backed George Osborne's austerity programme whilst led by Nick Clegg, most Lib Dem members support social democratic policies. I have no doubt that it would be possible to draw up a progressive alliance economic policy based on: investment, overturning cuts to welfare and local government, reversing the privatisation of the NHS and taxing the wealthiest, and multinational corporations, more heavily. It might even be possible to go further, to pledge to trial a basic income, given this has support from several figures in Labour, Greens and the SNP, and was formerly Lib Dem policy.
An economic agreement would, however be insufficient. A bold programme of constitutional reform would also be required, in order to attract the broadest coalition of voters. At its heart would be the introduction of some form of proportional representation for Westminster elections, so seats gained by each party match much more closely their national vote share. Electoral reform is a sine qua non of a progressive alliance - it ensures that such an alliance will only be needed once. After we have a proportional electoral system, centre left parties will be able to compete once again, without fear of splitting the anti-Conservative vote, and in the knowledge that they will be able to form a coalition once votes are counted. Of the parties that would make up a progressive alliance, only Labour does not currently support proportional representation, but it has supporters from all wings of the parliamentary party, from Jonathan Reynolds to John McDonnell, and, while not his priority, Jeremy Corbyn has expressed openness to top-up lists. While lukewarm, this tacit support for AMS/MMP, as used for the Scottish Parliament, the Welsh Assembly and the German Reichstag, is the most positive any Labour leader has ever been on proportional representation. So an agreement between centre-left parties on this crucial issue seems a genuine possibility.
A constitutional reform programme would need to go further. It should include: democratisation of the House of Lords, devolution to English regional assemblies, a written constitution and the right to recall MPs when a certain percentage of constituents are dissatisfied with their actions. Presumably the SNP and Plaid Cymru would have demands around increasing the powers of the devolved institutions in Scotland and Wales; these should be easy to grant. Such a radical programme would demonstrate the need for a one off electoral pact - it should be presented as coming together in order to democratise Britain once and for all.
There will be opponents of a progressive alliance from members of all the constituent parties. The smallest parties, the Greens and Plaid Cymru, have the most to gain, and are thus likely to be the most enthusiastic. As for Liberal Democrats, some members see themselves as equidistant between the two main parties and would not wish to side squarely with Labour. But I think the promise to bring in proportional representation would make it a reasonably easy sell - it has been a cherished aim of the party for a hundred years, and would guarantee them far greater representation in the House of Commons in all future elections. Labour will be the toughest nut to crack. If Labour MPs think they have a chance of winning the next election outright they will not agree to any kind of pact. But if that prospect seems out of reach, they may be more willing to take risks, especially if there is the prospect of stopping the Conservatives ever again ruling the country with only the support of a minority of the population. And there is historical precedent - Labour's initial parliamentary success in 1906 came as a result of an electoral pact with the Liberals, and its 1997 landslide victory would not have been possible without extensive tactical voting by Labour and Liberal Democrats voters - backing whichever party was best placed to beat the Tories in their constituency. Further, a progressive pact offers a partial answer to Labour's ongoing civil war - if you are going to make a pact with parties on both your left and right, it should be possible to simultaneously make a pact between the factions within your own party. The Tories can only be beaten by a broad coalition - whether comprised of multiple parties or one exceptionally diverse one.
An electoral pact is not a panacea. There are many seats in which only Labour, Conservatives and UKIP receive a significant number of votes. In those seats, it is down to Labour to propose a platform visionary enough to inspire non voters and those who have previously supported UKIP. Such a platform must be, as Paul Mason has argued, based on economic radicalism - proposing measures that would make a serious difference to the standard of living of people on average and below average incomes. But even in seats like these, a progressive alliance could shift the whole narrative of the election, moving away from a story of multiple parties all of whom criticise the other in favour of a stark choice - do you want to be governed by the Conservatives or do you want something different? The progressive parties must be honest enough to admit it - this is the only way to defeat the Tories in 2020.