Britain’s Conservatives have warned that Labour is on course for a record-breaking victory and has all but conceded defeat a day before polling stations even opened.

YouGov’s final seat projection published on Wednesday (British time) put Labour on track to win a majority of 212 seats in Thursday’s election – the largest of any party since 1832.

Such a wipeout would end 14 years of Conservative government — with ministers such as Jeremy Hunt losing their seats — and hand Keir Starmer the keys to No.10 Downing Street.

Both Starmer and Conservative Prime Minister Rishi Sunak kicked off the last day of campaigning warning voters of dire economic consequences if the other man won.

But, facing predictions of the worst result in the party’s history, the Conservatives turned their focus to damage limitation, saying they needed to hang on to enough seats to provide an effective opposition to a Labour government.

“I totally accept that where the polls are at the moment means that tomorrow is likely to see the largest Labour landslide majority, the largest majority that this country has ever seen,” Conservative minister Mel Stride told the BBC.

“What therefore matters now is what kind of opposition do we have, what kind of ability to scrutinise government is there within parliament.”

Asked about Stride’s comments, Sunak told ITV: “I’m fighting hard for every vote”.

Rupert Murdoch-owned tabloid newspaper The Sun endorsed Labour and Starmer on Wednesday, saying in an editorial published online: “It’s time for a change”.

“The insurmountable problem faced by the [Conservatives] is that – over the course of 14 often chaotic years – they have become a divided rabble, more interested in fighting themselves than running the country,” the newspaper, which has backed the Conservatives at every election since 2010, said.

Labour’s final campaign push focused on its fear that voters could see the result as a foregone conclusion and stay at home during polling on Thursday, or register protest votes with smaller parties.

Starmer said Stride’s comments were an attempt to lure wavering voters into not casting their ballots after polling opens at 4pm (AEST).

“I say: If you want change, you have to vote for it. I want people to be part of a change. I know there are very close constituencies across the country,” he told the BBC.

“I don’t take anything for granted, I respect the voters, and I know that we have to earn every vote until 10 o’clock tomorrow night and we will do that.”

Labour leader Keir Starmer on the campaign trail. Photo: Getty

Starmer’s campaign has been built around a one-word promise of “change”, tapping into discontent at the state of Britain’s stretched public services and falling living standards – symptoms of a sluggish economy and political instability.

Sunak has sought to persuade voters that his 20 months in charge have set the economy on an upward path after the external shocks of Covid-19 and the war in Ukraine, and drawn a line under years of turmoil overseen by his Tory predecessors.

He says Starmer will have to put up taxes to implement Labour’s agenda for change and the bigger its win, the more emboldened Starmer would be to raise taxes beyond those he has already outlined.

Rishi Sunak with supporters at his final rally at Romsey Rugby Football Club. Photo: Getty

Having failed to close Labour’s roughly 20-point opinion poll lead, Sunak turned to former prime minister Boris Johnson – the man he helped turf out of office in 2022 – inviting him to speak at a late-night Conservative rally on Tuesday.

Johnson, one of British politics’ most recognisable figures and the man who delivered the party a landslide win in 2019, made his first big public appearance of the campaign with a speech that listed many of his own achievements and gave little personal endorsement to Sunak.

“None of us can sit back as a Labour government prepares to use a sledgehammer majority to destroy so much of what we have achieved,” he said.

-with AAP