Labour faces the prospect of being routed in its northern heartlands if the party fails to fend off a challenge by Ukip in the upcoming Stoke by-election, Clive Lewis has warned.

Mr Lewis, the shadow Business Secretary, who is also a close ally of Jeremy Corbyn, said there are “swathes of the country, like in Stoke, where we are hanging on by the fingernails to keep Ukip at bay”.

Speaking to his Norwich South constituents on Friday evening Mr Lewis suggested if Paul Nuttall, the Ukip leader, emerged victorious in the Stoke-on-Trent Central by-election in two weeks’ time then the “politics of Trump” in Westminster could have a “domino effect”.

“There are swathes of this country, like in Stoke, where we are hanging on by the fingernails to keep UKIP at bay,” he said. “And if Ukip make a breakthrough in Stoke and if they make a breakthrough in parts of the North there will be a rout.”

“Some people may say, well that’s tough,” he added. “But I ask you to think about what that rout would make our Parliament look like. I genuinely ask you to do that.

“I was told if you break the whip at any stage in this vote you are responsible, potentially, for helping to let Paul Nuttall in. I don’t want Paul Nuttall to be in politics – I do not want the politics of Trump in Westminster. Once they have one voice, they have a base and it will be a domino effect."

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”.

On 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.

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But a spokesperson for the Labour leader told The Independent: “It is untrue that Jeremy Corbyn’s team or the Labour Party have been exploring collaborating with other parties in the Stoke-on-Trent Central by-election, informally or otherwise.”

At the meeting with his constituents on Friday, Mr Lewis also reiterated that he is prepared to resign from his post in the Shadow Cabinet later this week at third reading of the Government’s EU Withdrawal Bill – the legislation needed to invoke Article 50 of the Lisbon Treaty.