Theresa May is to warn that the consequences of failing to get the right Brexit deal will be “dire” for ordinary working people.

In a speech in Wales, the Prime Minister will seek to persuade voters that she should lead the negotiations with the European Union, rather than Jeremy Corbyn.

According to an advance copy of her remarks, she will make clear how quickly the process will start to move after the election on 8 June.

“There are just 17 days to go until this crucial General Election. Just 11 days after that, the European Union wants the Brexit negotiations to begin,” she says.

"The UK's seat at the negotiating table will be filled by me or Jeremy Corbyn. The deal we seek will be negotiated by me or Jeremy Corbyn.

"There will be no time to waste and no time for a new Government to find its way. So the stakes in this election are high… We need someone representing Britain who is 100 per cent committed to the cause, not someone who is uncertain or unsure, but someone utterly determined to deliver the democratic will of the British people.

"Because if we don't get this right, the consequences for the United Kingdom and for the economic security of ordinary working people will be dire. If we do, the opportunities ahead are great.”

Mr Corbyn, meanwhile, has issued a last-ditch appeal to students who have not registered to vote to do so before Monday's 11.59pm deadline so that they can support Labour's plans to scrap university tuition fees in the election.

"Students will benefit from having more money in their pockets, and we will all benefit from the engineers, doctors, teachers and scientists that our universities produce,” he said.

Polls have showed a narrowing of the Conservatives’ once seemingly unassailable lead over Labour.

The latest put the gap between the two parties to nine percentage points. The Survation survey for ITV's Good Morning Britain showed the Conservatives on 43 per cent, down five points on the previous week, and Labour up five on 34 per cent.

UK General Election 2017 Show all 47 1 /47 UK General Election 2017 UK General Election 2017 12 June 2017 British Prime Minister Theresa May leaves 10 Downing Street for the 1922 committee on June 12, 2017 in London, England. British Prime Minister Theresa May held her first cabinet meeting with her re-shuffled team today Getty Images UK General Election 2017 12 June 2017 DUP leader Arlene Foster stands alongside deputy leader Nigel Dodds as they hold a press conference at Stormont Castle as the Stormont assembly power sharing negotiations reconvene following the general election on June 12, 2017 in Belfast, Northern Ireland. Discussions between the DUP and the Conservative party are also continuing in the wake of the UK general election as Prime Minister Theresa May looks to form a government with the help of the Democratic Unionist parties ten Westminster seats. 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Getty Images UK General Election 2017 12 June 2017 British Prime Minister Theresa May (C, L) holds the first Cabinet meeting of her new team. Getty UK General Election 2017 11 June 2017 British Prime Minister Theresa May attends church in her constituency with her husband Philip May, a few days after disappointing results in a general election. Rex Features UK General Election 2017 9 June 2017 Leader of the Labour Party Jeremy Corbyn leaves Labour Party HQ this morning, following a general election yesterday. Parliament is hung, with no individual party gaining an overall majority. Post general election reaction. Rex UK General Election 2017 9 June 2017 BELFAST, NORTHERN IRELAND - JUNE 09: DUP leader and Northern Ireland former First Minister Arlene Foster (C) holds a brief press conference with the DUP's newly elected Westminster candidates who stood in the general election Getty Images UK General Election 2017 9 June 2017 A " Get May Out" demo took place opposite the gates of Downing Street, calling for May to resign, after the shock election results and Mays coalition with the DUP. Rex Features UK General Election 2017 9 June 2017 A demonstrator wears a mask depicting Britain's Prime Minister and leader of the Conservative Party Theresa May, poses with a mock gravestone bearing the words "Hard Brexit, RIP", during a protest photocall near the entrance 10 Downing Street in central London AFP/Getty Images UK General Election 2017 9 June 2017 Britain's Prime Minister Theresa May arrives at the Conservative Party's headquarters in London Reuters UK General Election 2017 9 June 2017 Britain's Prime Minister and leader of the Conservative Party Theresa May flanked by her husband Philip delivers a statement outside 10 Downing Street in central Londo Getty UK General Election 2017 9 June 2017 Britain's Prime Minister and leader of the Conservative Party Theresa May leaves Buckingham Palace in London the day after a general election in which the Conservatives lost their majority Getty Images UK General Election 2017 9 June 2017 A TV cameraman watches the door of 10 Downing Street in London Getty Images UK General Election 2017 9 June 2017 Labour leader Jeremy Corbyn is greeted by his Office Director Karie Murphy as he arrives at Labour Party HQ in Westminster, London, after he called on the Prime Minister to resign, saying she should 'go and make way for a government that is truly representative of this country' Dominic Lipinski/PA Wire UK General Election 2017 9 June 2017 Britain's Prime Minister Theresa May arrives at the Conservative Party's headquarters with her husband Philip in London REUTERS/Peter Nicholls UK General Election 2017 9 June 2017 Ukip leader Paul Nuttall speaks during a press conference at Boston West Golf Club where he announced that he is standing down as party leader Joe Giddens/PA UK General Election 2017 9 June 2017 Ruth Davidson, leader of the Scottish Conservatives, leaves the counting centre for Britain's general election with her partner Jen Wilson in Edinburgh, Scotland REUTERS/Russell Cheyne UK General Election 2017 9 June 2017 Scottish Labour leader Kezia Dugdale celebrates with candidate for Edinburgh South Ian Murray as he retains his seat at the Meadowbank Sports Centre counting centre in Edinburgh, Scotland Getty Images UK General Election 2017 9 June 2017 First Minister Nicola Sturgeon speaks to the media at the Emirates Arena in Glasgow, as counting is under way for the General Election Andrew Milligan/PA Wire UK General Election 2017 9 June 2017 Scottish Conservative leader Ruth Davidson at Meadowbank Sports Centre in Edinburgh, as counting is under way for the General Election PA UK General Election 2017 9 June 2017 Scottish National Party (SNP) leader Nicola Sturgeon reacts at the Emirates Arena in Glasgow, Scotland EPA UK General Election 2017 9 June 2017 Jeremy Corbyn, leader of Britain's opposition Labour Party, arrives at the Labour Party's Headquarters in London REUTERS/Marko Djurica UK General Election 2017 9 June 2017 UKIP Leader Paul Nuttall leaves in a car following the vote count for the constituency of Boston and Skegness in Boston, England Anthony Devlin/Getty Images UK General Election 2017 9 June 2017 British Prime Minister and Conservative Party leader Theresa May speaks at the declaration at the election count at the Magnet Leisure Centre in Maidenhead, England. 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Getty Images UK General Election 2017 6 June 2017 A supporter wears a pair of Jeremy Corbyn decorated tights at a general election campaign event in Birmingham, central England, on June 6, 2017. Britain goes to the polls on June 8 to vote in a general election only days after another deadly terror attack in the nation's captial. AFP/Getty Images UK General Election 2017 6 June 2017 A picture taken in London, shows election leaflets from various parties displayed ahead of the United Kingdom's general elections. Britain goes to the polls on June 8 to vote in a general election only days after another terrorist attack on the nation's capital AFP/Getty Images UK General Election 2017 6 June 2017 Election workers, George Gaunt and Luca Tragid deliver the first ballot boxes, on the Royal Mile in Edinburgh AFP UK General Election 2017 6 June 2017 British Prime Minister Theresa May meets with Conservative party supporters during an election campaign visit to a bakery during an election campaign visit on June 6, 2017 in Fleetwood, north-west England. 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Britain goes to the polls on June 8 to elect a new parliament in a general election Getty Images UK General Election 2017 22 May 2017 Liberal Democrat leader Tim Farron poses for a selfie taken by carer April Preston during a General Election campaign visit to the Barlow Medical Centre, in Didsbury, Manchester Yui Mok/PA UK General Election 2017 22 May 2017 Britain's Prime Minister Theresa May speaks at an election campaign event in Wrexham, Wales Reuters UK General Election 2017 22 May 2017 Britain's main opposition Labour Party leader Jeremy Corbyn, and Labour's former deputy Prime Minister, John Prescott, exit the party's general election campaign 'battle' bus as they arrive at an event in Kingston upon Hull, northern England Getty Images UK General Election 2017 22 May 2017 Britain's main opposition Labour Party leader Jeremy Corbyn walks with supporters between venues, before speaking again at another general election campaign event in Kingston upon Hull, northern England Getty Images UK General Election 2017 22 May 2017 An anti-fox hunting protester is taken away and arrested by police outside the venue where Britain's Prime Minister Theresa May was due to launch the Welsh Conservative general election manifesto at Gresford Memorial Hall in the village of Gresford, near Wrexham, North Wales, on May 22, 2017. 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Ms May is under pressure over her party’s plan to overhaul the funding of social care, which would mean elderly people would have to pay for care in their own home if they have total assets of £100,000 or more.

Foreign Secretary Boris Johnson refused to be drawn over the weekend on suggestions that the Cabinet was not consulted about the plan.

Ministers were adamant there would be no going back on the plan, although they said there would be a green paper on health and social care released over the summer if the Tories were returned to power on 8 June.

However Liberal Democrat leader Tim Farron vowed to mobilise a national campaign against what he called the "dementia tax" because of the potential impact on sufferers of the debilitating condition.

He said he would be seeking the support of medical organisations and charities including former prime minister David Cameron who is now president of Alzheimer's Research UK.

"Caring for our elderly must be above party politics and that is why I want to urge anyone who opposes the Conservatives' plans to come together to stop it," he said.