Jeremy Corbyn’s chances of winning an overall majority for Labour in the 12 December general election are “as close to zero as one can safely say it to be”, Professor ​Sir John Curtice has said.

But Mr Corbyn could still enter 10 Downing Street as prime minister next month, the polling guru said.

Speaking at Westminster, the Strathclyde University election expert said that the most likely outcomes based on current polling is either a fairly sizeable Tory majority delivering Brexit on Boris Johnson’s terms or a hung parliament resulting in a minority Labour administration propped up by other parties delivering a second referendum.

And the deciding factor in determining between these outcomes may be the performance of Mr Johnson in what is effectively an “unpopularity contest” between two leaders who each provoke historically high levels of dissatisfaction among voters.

Comparing the Conservative leader to a Ming vase, Prof Curtice said: “Boris Johnson is potentially a really valuable asset. You just have to make sure he doesn’t end up on the floor.”

Top 10 marginal seats to watch at the general election Show all 10 1 /10 Top 10 marginal seats to watch at the general election Top 10 marginal seats to watch at the general election North East Fife Currently held by the SNP with a majority of 2 Getty Top 10 marginal seats to watch at the general election Kensington Currently held by Labour with a majority of 20 Getty Top 10 marginal seats to watch at the general election Perth and North Perthshire Currently held by the SNP with a majority of 21 Getty Top 10 marginal seats to watch at the general election Dudley North Currently held by independent, formerly Labour, MP Ian Austin with a majority of 22 LivingInMediocrity Top 10 marginal seats to watch at the general election Newcastle-under-Lyme Currently held by Labour with a majority of 30 Derek Harper Top 10 marginal seats to watch at the general election Southampton Itchen Currently held by the Conservatives with a majority of 31 Rob Candish Top 10 marginal seats to watch at the general election Richmond Park Currently held by the Conservatives with a majority of 45 Robin Webster Top 10 marginal seats to watch at the general election Crewe and Nantwich Currently held by Labour with a majority of 48 Jaggery Top 10 marginal seats to watch at the general election Glasgow South West Currently held by the SNP with a majority of 60 Alec MacKinnon Top 10 marginal seats to watch at the general election Glasgow East Currently held by the SNP with a majority of 75 Christine Johnstone

He pointed to Mr Johnson’s fumbling response to floods in Yorkshire and the midlands as an example of the kind of unpredictable event that could yet upend the current 10-point Conservative lead in the polls in the remaining four weeks of campaigning.

Prof Curtice stressed he was not making a forecast of the election result.

But he said: “With a 10-point lead, however you look at it, if that were to transpire in the ballot box, it must be highly likely that the Conservatives will get an overall majority of a size sufficient to enable them to get the withdrawal treaty through.

“Below 6-7 points, the odds swing in favour of a hung parliament. Just because the Tories are ahead in the polls, it doesn’t mean Boris is going to get a majority.”

And he added: “The chances of the Labour Party winning a majority are frankly as close to zero as one can safely say it to be, given that they look to be incapable of regaining anything in Scotland.”

Prof Curtice told reporters the 2019 election was shaping up as a “binary” contest.

With the Democratic Unionist Party implacably opposed to Mr Johnson’s Brexit deal, and the Liberal Democrats and Scottish National Party keen to secure a second EU referendum, another minority Conservative administration propped up by a smaller party seemed highly unlikely, he said.

“Either Boris gets a majority and we are leaving the EU on the terms he has negotiated and will negotiate, or we get a hung parliament in which we have to anticipate a minority Labour administration will be put in to apply for an extension and we will have a referendum.”

John Curtice’s exit poll proved remarkably accurate at the 2017 election (BBC)

There is only a “narrow range of results” which would produce the kind of drama and uncertainty seen in the 2017 parliament, he said.

But he said that the binary choice reflected the balance of opinion seen in polls, with parties prepared to hold a second referendum taking about 52 per cent of support in total and those in favour of Brexit around 48 per cent, compared to the current 53-47 split in favour of Remain in polling on EU membership.

“The reason why the Conservatives are at the moment in pole position in the election is not to do with the popularity of Leave itself, but the fact that the Remain vote is more split,” he said, pointing to research suggesting about three-fifths of Brexiteers plan to vote Tory and only two-fifths of Remainers plan to back Labour.