LONDON — UK opposition Labour party sought on Tuesday to exploit the ruling Conservatives' weakness on healthcare and divert attention from its own mixed message on Brexit two days before Britons head to the polls.

But its hopes of staging a comeback before Thursday's general election were hobbled by a leaked recording in which Labour's own health spokesman called his party's prospects "dire".

"It's abysmal out there," Jonathan Ashworth said in a recording published by a right-wing website and later tweeted by Prime Minister Boris Johnson.

"They can't stand (Labor leader Jeremy) Corbyn and they think Labour's blocked Brexit."

Ashworth told the BBC the tape was real but he was speaking in jest.

Opinion polls show Johnson's Conservative party enjoying a 10-point lead in an election he has called the "most important in a generation".

Johnson's minority government hopes to secure a majority that would let him pull Britain out of the European Union by the end of next month.

Yet pollsters were almost unanimously wrong about the outcome of Britain's last election in 2017 after a last-minute surge by Corbyn — a 70-year-old leftist who is most at home campaigning on the stump.

A ruling party memo published by the pro-Conservative Daily Telegraph newspaper warned that just 40,000 votes in 12 constituencies could see Corbyn become Britain's next leader.

Corbyn himself believes he could reach those voters by focusing on the state-funded National Health Service (NHS).

Labour claimed on Tuesday that nearly 4,700 deaths between October 2018 and November 2019 could be attributed to "patient safety incidents" caused by NHS staffing constraints.

"I do not blame the nurses. I do not blame the doctors. I do not blame the health service," Corbyn told a group of cheering supporters in central England.

"I blame the government that has underfunded our NHS."

Labour accused Johnson of abandoning the principle of free treatment for all by opening up the NHS to pharmaceutical giants in a new trade deal with US President Donald Trump.

Both Johnson and Trump deny the claims.

Surveys show the NHS being almost as important to voters as Brexit itself.

They also point to a general mistrust of Corbyn's non-committal position on Brexit and frustrations over the Conservatives' handling of the NHS.

Johnson has campaigned on his government's determination to "get Brexit done" and honor the result of the 2016 referendum on European Union membership.

Analysts suggested Labour's ability to keep the focus on health and other social issues could be vital for the result.

"This kind of last-minute thing, that really does ram home Labour's core message, at this point could nudge a few people in certain vital constituencies to vote Labour," University of Nottingham Professor Steven Fielding said.

"At this point in time, it could be the difference between a majority Conservative government and a hung parliament."

Johnson tried to seize back the momentum by ramming a digger marked "get Brexit done" through a wall bearing the sign "gridlock" at a factory plant whose owners are a major donor to the Conservatives.

Labour quickly countered with an edited version of the clip that made it look like Johnson was tearing down the NHS.

Britain's partisan media has assumed a dominant role in the final stretch of a manic five-week campaign that has seen Corbyn and Johnson spend most of their time on the road.

The Labour-supporting Daily Mirror newspaper devoted its first seven pages on Tuesday to the state of the NHS.

"Another day, another heartbreaking image of a sick child that shames the Tories of starving the NHS of cash," the newspaper wrote next to a photo of a sick baby resting in an armchair because of a lack of beds.

That followed its publication on Monday of a picture of a boy sleeping on a hospital floor while he waited to be treated.

Johnson drew criticism on Monday when he was confronted on camera and asked to comment on the photograph of the boy on a journalist's phone.

He grabbed the reporter's phone and put it in his pocket before handing the phone back saying it was a "terrible, terrible photo". — AFP