Conservative MP and former health minister Dan Poulter has defected to Labour.
The MP for Suffolk Central and Ipswich North, with a majority of 23,321 at the last election, has indicated he is not planning to stand at the next general election.
The defection was revealed in an article on The Observer website, in which the part-time GP outlined why he was switching parties.
He said: “The chaos of today’s fragmented patchwork of community addiction services – making A&E the default location for people to get treatment and help – has added pressure to an already overstretched service.
“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.
“It is this which has led me today to have resigned from the Conservative party to focus on my work as a doctor and to support Keir Starmer.”
Sky’s Jon Craig said: “This is a real blow for the Conservatives and a massive coup for the Labour Party.”
Wes Streeting said in a tweet: “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.”