Jeremy Corbyn 'kept away from voters' by election strategists in Stoke

The party faces a difficult contest against Ukip's Paul Nuttall

According to reports, the leader is considered a liability as Labour aims to keep its seat in Stoke (Getty)

Labour by-election campaigners in Stoke are keeping Jeremy Corbyn away from voters because he is "not a plus on the doorstep", it has been claimed.

The party faces a tough battle in the heartland seat, where leader Paul Nuttall is hoping to become Ukip's second MP by defeating Labour candidate Gareth Snell.

Former shadow Business Secretary Clive Lewis, who resigned on Thursday over the Brexit vote, said Labour was "hanging on at the fingernails" in the Leave-favouring region.

A source told the Telegraph that Mr Corbyn is "not a plus on the doorstep, that's for certain". Mr Corbyn did visit the constituency at the end of January.

The Independent has approached Labour for comment.

Questioned by Andrew Marr on Sunday morning about Mr Corbyn's "catastrophic" favourability ratings, deputy Labour leader Tom Watson said: "Jeremy knows what he has to do to win an election. This is not the time for a leadership election. He got a second mandate.

"He is now the established leader of the Labour Party. It is his duty to lead the official opposition through a period of unprecedented economic uncertainty, and he will be tested in that.

"Winning by-elections is obviously a good thing for political parties. I don't know whether we're going to win these by-elections or not, the campaign teams on the ground are running a good campaign, we've got two good candidates. They're quietly confident that we'll get a good result."

The crucial contest in Stoke, to be held on 23 February, follows the resignation of senior Labour MP Tristram Hunt last month to become the director of the Victoria & Albert Museum in London.

At the 2015 general election Mr Hunt, the former shadow Education Secretary and well-known critic of the Labour leader, held onto the seat with a majority of 5,179. Ukip came second in the constituency, just 33 votes ahead of the Conservatives.

The 40-year-old Ukip leader Mr Nuttall was confirmed as the party’s candidate last month and has promised to raise issues the “establishment parties would prefer to brush under the carpet”.

Last Saturday Labour had dismissed suggestions the party had been exploring a collaboration with the Liberal Democrats in Stoke to avoid the Ukip leader gaining ground. The Guardian had claimed a senior figure from the leader’s office had asked an intermediary to probe a potential pact between the two parties.

It has also launched an apparent "attack ad" against Mr Nuttall, in another move that signifies he is considered a real threat.

Mr Corbyn tweeted the video about Mr Nuttall with the warning: "Voters of Stoke, if you value your NHS then don’t vote for this man who wants to sell it off #CarefortheNHS."

In the footage, MEP Mr Nuttall brands the NHS "a monolithic hangover from days gone by".