THE election is poised on a knife edge as a major poll slashed Boris Johnson’s predicted Commons majority from 68 two weeks ago to just 28 this week with only a day’s campaigning to go.

The prospect of another hung parliament looms as the Prime Minister and Jeremy Corbyn prepare to make their final pitches for power with Mr Johnson urging people to vote Conservative to keep Britain out of the “quicksand” of Brexit and the Leader of the Opposition saying a vote for Labour is a “vote for hope” to save the NHS.

As the two main party leaders cross-cross the country in the last hours of campaigning, the YouGov poll suggested the Tories were on course for a 28-seat majority but this was less than half the number, 68, predicted last month, suggesting the election is tightening sharply as it nears its end.

The snapshot based on 100,000 interviews, which accurately forecast the 2017 election result, suggests the Tories will pick up 339 seats, up 22 on 2017, Labour 231, down 31, the SNP 41, up six, and the Liberal Democrat’s 15, up three.

However, given the possible range of the prediction, which could put the Tories on as low as 311 seats, then the pollster suggested another hung parliament could not be ruled out.

READ MORE: Boris Johnson: Block Indyref2 and deliver a good Brexit for Scotland

Writing in The Herald today, the two main party leaders make one last appeal to Scottish voters.

Mr Johnson declares: “This Thursday, the very future of our Union is on the line. Only by voting for the Scottish Conservatives can you end the threat of a second independence referendum for good.”

Emphasising his “absolute guarantee” not to grant Nicola Sturgeon her desire to hold a second vote on Scotland’s future, the Tory leader insists Mr Corbyn would, by contrast, “sell out Scotland in a heartbeat to get into government and cave in to her demand for an independence referendum in less than 12 months’ time”.

Mr Corbyn, who will make a speech in Glasgow this morning, places his emphasis on his key campaign theme: healthcare. He says: “On Friday, you can wake up to either a Tory Government ready to sell out our NHS to Donald Trump or a Labour Government that will protect it and invest in it. The choice is clear.”

READ MORE: Jeremy Corbyn: A society where no-one is left behind

The Labour leader dismisses the First Minister’s “simplistic solution” to Scotland’s challenges in her call for another referendum, warning an independent Scotland would simply herald another decade of public spending cuts.

“So, at this election, the only prospect for real change – not just in raising living standards but in shifting wealth and power from the few to the many and reviving the collective fabric of Scotland’s society – is with Labour,” Mr Corbyn declares.