The size of Boris Johnson's likely majority has halved in the final fortnight of the election campaign, according to a highly anticipated opinion poll that raises the prospect of another hung Parliament.
In a result that appears to confirm growing Tory nerves over Thursday's outcome, the polling model that accurately predicted the United Kingdom's shock 2017 election result suggests the Conservatives are now on course to win 339 seats compared to 231 for Labour, 15 for the Liberal Democrats and 41 for the Scottish National Party.
If replicated on election day, that would give Johnson a comfortable majority of 28 seats and the best result for the Conservatives since Margaret Thatcher's 1987 victory.
But the prediction is substantially down from the 68-seat majority the YouGov poll reported only two weeks ago.
The margin of error could put the final number of Conservative seats anywhere from 367 to 311.
"This means that we absolutely cannot rule out the 2019 election producing a hung Parliament - nor can we rule out a larger Conservative majority," said YouGov director of political research Anthony Wells.
The so-called multilevel regression and post-stratification (MRP) poll is based on 105,612 interviews between December 4 and December 10. Using other information and data, the model makes seat-by-seat predictions.
Johnson on Tuesday, London time, warned that another hung Parliament would imperil progress on Brexit and see Labour leader Jeremy Corbyn take the keys to Downing Street.
Johnson would struggle to retain power in a hung Parliament because the Tories have few allies on the crossbench.
The YouGov poll shows the Tories command a 43 per cent share of the vote compared to 34 per cent for Labour - a result which would produce a likely loss of 31 seats for the opposition in its worst result since 1983. The Liberal Democrats have faded to just 12 per cent.
"Most of the seats changing hands are ones Labour won in 2017, passing back to Tory control," the pollster said in a newly released summary. "What happens in these constituencies is key to deciding whether Boris Johnson has a majority and how large it may be.
"Since our last model in November it’s clear that Labour has pulled back many of these seats. In November, they were set to lose 43 to the Conservatives but this has now dropped to just 29.
"While our model shows a 28-seat majority for the Conservatives there are a number of areas which could be incredibly tight - there are 85 seats where the leading party is ahead by 5 per cent or less.
Jeremy Corbyn. Labour, which is lagging behind the Tories in the polls, is under pressure to woo investors.
"In 25 seats the Tories are ahead by 5 per cent or less and Labour is in second, meaning that the party would only need to make small gains in order to steer us towards a hung Parliament.
"There are also 31 seats where Labour lead the Conservatives by 5 per cent or less. If the Tories outperform expectations in these seats they would have a much more comfortable majority."
