A Tory MP and former health minister has defected to Labour in protest against the Tories’ “rightward drift” and neglect of the NHS, in a blow to the Prime Minister.

Dr Dan Poulter, a working medic, has quit Rishi Sunak’s party saying it is “failing” the health service and that he could no longer “look my NHS colleagues in the eye” as a Conservative.

He will take the Labour whip until the general election but will not be running again as the MP for Central Suffolk and North Ipswich, he wrote in the Observer.

Dr Poulter told the newspaper the Conservative Party “feels like it has become a nationalist party of the right”, having seen a “rightward drift” since David Cameron left Downing Street in 2016.

“The health service has ceased to be an area of priority for the Conservative Party, and that is now showing in the strain on the front line and the deterioration of care for patients,” he said.

He added that he had come to the conclusion that “the only cure is a Labour government”, and that he would support Sir Keir Starmer and shadow health secretary Wes Streeting before and after the general election on NHS policy.

The Conservative Party hit back that he was “wrong” to say only the Opposition could improve the health service.

Speaking to the BBC’s Laura Kuenssberg, Dr Poulter said: “I found it increasingly difficult to look my NHS colleagues in the eye and my patients in the eye and my constituents in the eye with good conscience.

“And I feel that the NHS deserves better than it has at the moment in terms of how it’s run and governed.

“The party I was elected into valued public services, it had a compassionate view about supporting the more disadvantaged in society. I think the Conservative Party today is in a very different place. Its focus is not on delivering or supporting high-quality public services.”

Labour leader Sir Keir said it was “fantastic to welcome Dr Dan Poulter to today’s changed Labour Party.

“It’s time to end the Conservative chaos, turn the page and get Britain’s future back. I’m really pleased that Dan has decided to join us on this journey.”

Mr Streeting said on social media site X: “Proud to welcome Dr Dan Poulter MP to the @UKLabour Party.

“As a frontline clinician, he’s seen the damage that 14 years of Conservative government have done to our NHS.

“Delighted to have his support and look forward to working with him, especially on mental health reform.”

The defection is a significant blow to Mr Sunak less than a week before council and mayoral elections in which the Tories are expected to suffer heavy losses.

It is the first time a Conservative MP has crossed the floor to Labour since Christian Wakeford did so in 2022.

Dr Poulter’s move is the second defection under Mr Sunak, after former Tory deputy chairman Lee Anderson ditched the party for Reform earlier this year.

It is likely to spook already restive Tory MPs and fuel doubts over Mr Sunak’s leadership.

In a letter to the Prime Minister, Dr Poulter wrote: “I have decided, in all professional conscience, that I can no longer continue as a member of the Conservative Party.

“Regrettably, I have come to the conclusion that only the Labour Party has the trust and the will to restore a failing health service which is currently unable to deliver the care patients need and deserve.”

He also “respectfully” urged the Prime Minister to “call a general election as soon as you feel able”.

Mr Sunak has said the election will come in the second half of the year, but a disastrous set of mayoral and council elections on May 2 could force his hand, either by leading to a challenge to his leadership or by persuading him that an earlier polling day could be a better solution than limping on with a divided party.

Writing in the Observer, Dr Poulter said that, working 20 night shifts as am A&E mental health doctor over the past year, he had seen patients suffering from serious psychosis waiting days for a mental health bed, which would often end up being hundreds of miles from their homes.

He wrote: “The mental toll of a service stretched close to breaking point is not confined to patients and their families. It also weighs heavily on my NHS colleagues who are unable to deliver the right care in a system that simply no longer works for our patients.”

The Observer reported that discussions had been going on for months between the MP and senior Labour figures about the timing of his defection and roles he could take on advising the party on its policies, while only half a dozen people were let in on the plans.

Dr Poulter was first elected to Parliament in 2010. He held his Central Suffolk and North Ipswich seat at the 2019 election with a majority of 23,391.

A Tory Party spokesperson said: “For the people of Central Suffolk and North Ipswich this will be disappointing news. What Dan says is wrong as Sir Keir Starmer has no plan for our NHS.

“Under the Conservatives we are raising NHS funding to a record £165 billion a year, helping it recover from the effects of the pandemic and driving forward its first ever long-term workforce plan so that we train the doctors and nurses we need for the future in our country.

“Thanks to our plan, we have already virtually eliminated the longest waits and overall waiting lists have fallen by 200,000 in the last five months – and we will go further to make sure everyone gets the world-class care they need.

“This stands in stark contrast to the Welsh NHS – run into the ground by the Welsh Labour government over the last 25 years which has waiting lists and waiting times way beyond what is being delivered in England.”