An Oldham MP has launched a ferocious attack on the Prime Minister in the wake of the double by-election defeat for the Conservatives which triggered the resignation of party co-chairman Oliver Dowden.

In a scathing statement Debbie Abrahams, who represents Oldham East and Saddleworth, said Boris Johnson has “lost any moral authority he had".

She said: “To be fair to Oliver Dowden, he wasn’t who people on the doorstep said they had no trust in, it was the Prime Minister.

"He has lost any moral authority he had as a result of his own disgraceful behaviour and the nasty culture that he propagates.

“In addition to the chairman of the Conservative Party resigning, his ethics advisor had had enough of him and resigned earlier this week as well.

"Judging by the by-election results, the British people have had enough of him too.

“Unfortunately, I doubt the Prime Minister will do the right thing and take responsibility for the mess the country is in and the hardship so many are enduring.

"He is undoubtedly the worst Prime Minister this country has had in living memory."

Speaking at a Commonwealth summit in Rwanda on Friday, the day after the by-election defeat, Mr Johnson vowed to “listen” to voters and “keep going”.

The Prime Minister told broadcasters: “It’s absolutely true we’ve had some tough by-election results.

"They’ve been, I think, a reflection of a lot of things, but we’ve got to recognise voters are going through a tough time at the moment.

“I think as a government I’ve got to listen to what people are saying – in particular to the difficulties people are facing over the cost of living, which I think for most people is the number one issue.

“We’ve got to recognise there is more we’ve got to do and we certainly will; we will keep going, addressing the concerns of people until we get through this patch.”

In an interview with Channel 4 News, Mr Johnson added: “I, of course, take responsibility for the electoral performance of the government.”