Will we wake up on Friday 13th December to a Boris Johnson landslide, or to a hung parliament in which Labour could form the next government with support from other opposition parties? Impressive campaigning efforts by the party’s grassroots membership have begun to narrow the gap. Today Datapraxis publish a new deep-dive report with unique data on 65 key Tory-Labour marginals that are still in play, as well as three of the most controversial three-way marginals.

These seats will decide the outcome of this election, together with a smaller number of constituencies where the Liberal Democrats or the SNP are the main challengers to the Conservatives. One thing is sure: an unprecedented number of voters are still undecided or could switch their votes.

Earlier in the campaign, we published a report on seven seats where Labour or the Liberal Democrats could defeat incumbent “big beast” Tory Brexiteers. Our estimate of a 48-seat Tory majority in that report was published on the frontpage of the Sunday Times, and was more optimistic for Labour than YouGov’s own forecast. We have seen real movement toward Labour since then. We continue to believe that Iain Duncan Smith, Steve Baker, Dominic Raab, Philip Davies, John Redwood, Zac Goldsmith and Boris Johnson are all vulnerable.

Labour began this campaign with a more aggressive strategy. The party high command were slow to realise the scale of the threat from Dominic Cummings’ brutally effective “get Brexit done” slogan in many of their heartland seats – the so-called “Red Wall”, where hundreds of thousands of Labour Leavers are already switching directly to the Tories.

After the first public release of YouGov’s own model, the party responded belatedly to this threat. This report identifies 45 seats as defensive battlegrounds for Labour, 32 of which are now in very serious jeopardy. Seats like Bolsover, Crewe & Nantwich and Lincoln and the Bolton, Wolverhampton and Stoke-on-Trent seats feature strongly.

There are, however, still at least 18 seats where Labour is the strongest challenger to the incumbent Conservatives and has some prospect of victory. Almost none are in the Leave-voting heartland town seats Labour aspired to win back. Instead, they are mostly to be found on what we call the “Southern Front”, in more Remain parts of England – places like Hendon, Chipping Barnet, Milton Keynes and Hastings & Rye. In all these seats, more naturally Liberal or Green voters and young first-time voters hold the key. A few Welsh seats are also in this category, if anti-Tory votes there coalesce behind Labour.

While the party is still behind in many of these seats, the polls have started moving in its direction. There is a real prospect of large-scale anti-Conservative or pro-Remain tactical voting, and millions of newly-registered younger voters mostly favour Labour – if they end up turning out. We also take a look at a handful of three-way marginals in London where Labour and the Lib Dems are vying to be the leading anti-Tory party. In Kensington in particular, it seems Labour’s Emma Dent Coad may be best placed; but we will publish constituency polls soon to update our assessment.

With just five days until the polls close, everything is still to play for. This report presents seat-by-seat data based on Datapraxis modelling of an extraordinarily large polling sample of 269,838 responses from YouGov between November 4th and 22nd, which factors in the trend line. We have used the cutting-edge technique called MRP (multi-level regression with post-stratification). Our decision to use a larger sample than YouGov themselves was driven by the non-binary nature of this election, with many more three or four-way fights than is normal. The super-sample of hundreds of thousands of respondents enables Datapraxis to pick up more signal about how different voter groups are moving locally than pollsters using smaller samples.

As many as one in five Labour Leave voters and a similar number of Conservative Remain voters are still undecided – a higher proportion than is typical this late in the campaign. These voters are “cross-pressured”; their Brexit position and value systems are at odds with their perceptions of the party they voted for in 2017. Unfortunately for Labour, both of these key undecided groups have very negative perceptions of Jeremy Corbyn. But both groups are very concerned about the NHS; and the impossibility of a Labour majority may assuage their concerns about its leader.

Our cluster analysis finds Labour’s core support concentrated among just two tribes: “The Green Left” and “Centre-Left Pragmatists”. On the Remain side of the divide, older “Progressive Cosmopolitan Pragmatists” who mostly vote tactically and “Younger Instagram Progressives” who care a lot about climate and dislike the right are key swing groups. “Young Apathetic Waverers” may also prove important – if they turn out. On the Leave side, three groups – the “Anti-Tory Heartlands”, “Older Brexit Swing Voters” and “The Older Disillusioned” are vulnerable to the Tories. Issues like the NHS, anti-austerity, a Green Industrial Revolution and economic hope could unite this diverse coalition.

Our research has found that “It’s time for real change” is a hugely powerful message, which even Cummings appears to feel threatened by according to his recent “Batsignal” blog. It is hard to argue with statements like “a million affordable homes – that’s real change.” “End austerity and rebuild Britain” is also very powerful message, in particular in majority-Leave heartlands. “For the many, not the few” remains a powerful contrast message. “We can’t afford five more years of the Tories” and “you can’t trust the Tories with the NHS” also cut through.

“Get Brexit sorted – give the people the final say” works well for most Labour voters, particularly Remainers. Labour Leavers connect better with statements like “put Brexit to bed within six months” or “get past Brexit and rebuild Britain”. But there is very little sign that Labour can win with its Leave voters if the topic remains on Brexit, such is the power of the “get Brexit done” fantasy. The party needs to move the conversation on rapidly to other issues.

“Our NHS is not for sale” is one of the most powerful and broadly appealing messages we have tested anywhere. People are concerned that their local hospital won’t be able to cope this winter, and large majorities of key groups believe the warnings that “Boris Johnson will sell the NHS to Donald Trump”. If Labour Leavers come back to the party in the final week, it will be first and foremost because of this.

I am sorry to say that there is absolutely no chance of a Labour majority in this election. The likeliest scenario remains a significant Tory majority. The best case for Labour is perhaps a minority government in a hung parliament. Its first task would be to organise a second referendum on Brexit. After that is put to bed, Labour’s fortunes could still rapidly revive, with the right strategy and leadership team. Its economic revival agenda is popular and timely, and the grassroots Labour movement is its greatest strength.