We could be on the verge of a genuinely historic general election outcome in Wales. That is the key message to emerge from the final Welsh Political Barometer poll of the 2019 election.

Our latest poll was conducted over the final weekend of the campaign. It once again asked people across Wales, how they would vote in the general election. As in our last poll, we have adjusted the standard voting intention question to take into account of the fact that not all parties are standing in all seats. Therefore, respondents were asked: “There will be a UK general election on 12 December 2019. The following candidates and parties will stand in your constituency. How do you intend to vote in the upcoming election?”

Here are the voting intention figures that the poll produced (with changes on our last Barometer poll, conducted in late November, in brackets):

Labour: 40% (+2)

Conservatives: 37% (+5)

Plaid Cymru: 10% (-1)

Liberal Democrats: 6% (-3)

Brexit Party: 5% (-3)

Greens: 1% (no change)

Others: 1 (no change)

These figures would enable the Labour party to continue their long run – unbroken since 1922 – of winning the most votes in Wales at every one of the last twenty-six general elections. But rarely if ever has the Tory challenge to Labour dominance been that strong. If our poll was reproduced on election day itself, this would be an historic result for the Conservatives in Wales. This would be their highest Welsh vote share since 1900 – thus, their highest ever in the era of universal (male) suffrage.

The squeeze on the smaller parties seen in our previous two Welsh polls continues, with the ‘big two’ now winning nearly eighty percent of all electoral support. The contrast with May, when between them the Conservative and Labour parties won little more than twenty percent of the vote in the European Parliament election, is staggering.

What might such support levels for the parties mean in terms of parliamentary seats? Using the standard method, of projecting the swings since the last general election indicated by this poll uniformly across Wales, gives us the following outcome in terms of seats (with projected changes from the 2017 result in brackets):

Labour: 20 (-8)

Conservatives: 16 (+8)

Plaid Cymru: 3 (-1)

Liberal Democrats: 1 (+1)

The seats to change hands would be as follows:

Conservative Gains from Labour: Alyn and Deeside, Bridgend, Cardiff North, Clwyd South, Delyn, Gower, Vale of Clwyd, Wrexham

Conservative Gain from Liberal Democrats: Brecon and Radnor (recapturing the seat the party won in 2017, but lost in the August by-election; the projection here is assuming uniform swings since June 2017)

Liberal Democrat Gain from Plaid Cymru: Ceredigion

Thus, our poll suggests that as well as winning the most votes, Labour would still come out ahead in Wales on seats. But twenty seats would equal Labour’s worst performance in Wales since the war, while it would be the best for the Conservatives in that era – even outdoing their showing in Margaret Thatcher’s 1983 landslide victory. The Welsh Conservatives would have made a very substantial contribution to delivering a parliamentary majority for Boris Johnson.

A major reason why Labour’s fightback in Wales appears to have stalled is that, unlike in 2017, Jeremy Corbyn has not been able to continue improving his personal ratings with the public. The improvement seen in our last poll has flattened out, and although the gap is smaller than it was at the start of the election, he continues to trail Boris Johnson on our ‘best Prime Minister’ question (with Johnson on 40 percent, up two points on our late November poll, compared to Corbyn being chosen by 33 percent, with the remainder of the sample choosing Don’t Know).

With just days to go now, things remain very much in the balance. It is well within the ‘margin of error’ in polls for Labour to retain many of the seats that our poll currently projects them to lose. But sampling errors work both ways: the picture could be even bleaker for Labour than is suggested here. Our new poll suggests that it is, for instance, far from inconceivable that the Labour party could be wiped out throughout north Wales in terms of parliamentary representation. And despite a less than flawless Welsh campaign, significant Conservative gains in Wales appear to be ever more likely.

The poll, for ITV-Cymru Wales and Cardiff University, had a sample of 1,020 Welsh adults and was carried out by YouGov from 6 to 9 December 2019.