Health Secretary Wes Streeting has put out a string of WhatsApp exchanges with Lord Mandelson including how he feared losing his London seat at the next general election.
The Ilford North MP also accused Israel of committing “war crimes before our eyes”.
On the economy, he told Lord Mandelson that he believed Chancellor Rachel Reeves and Sir Keir Starmer had “no growth strategy at all”.
Mr Streeting gave his message exchanges with the disgraced peer to Sky News for its political podcast Electoral Dysfunction, in a bid to explain their relationship.
In one of them dated March 2025, Mr Streeting tells of his worries about losing his London seat.
“I fear we’re in big trouble here - and I am toast at the next election.
“We just lost our safest ward in Redbridge (51% Muslim, Ilford S) to a Gaza independent.
“At this rate, I don’t think we’ll hold either of the two Ilford seats.”
Mr Streeting went on to explain: "There isn't a clear answer to the question: why Labour?"
Mandelson replied: "The government doesn't have an economic philosophy which is then followed through in a programme of policies."
Streeting replied: “No growth strategy at all.”
Mr Streeting retained his Ilford North seat in July 2024 with a majority of just 528, gaining 15,647 votes, with Independent Leanne Mohamad getting 15,119.
Ms Mohamad focussed her campaign against Streeting over Labour’s stance on the Israel-Hamas war.
Since then Labour has plunged in the polls, including to a record low in London of just 31% support.
Mr Streeting told Sky News that he would be standing again in Ilford North and he was “determined” to win the seat.
He said that a year on from his messages he was receiving “a lot of support” from constituents who either abstained or backed other main parties last time.
The Whatsapp exchanges reveal how close the Health Secretary was to Lord Mandelson, with both on the Blairite wing of the Labour Party.
Putting out the messages now may limit their impact on any future leadership bid by Mr Streeting.
He told Sky News' political editor Beth Rigby the messages showed he had "nothing to hide" in the messages and rejected her suggestion that they showed he had an "intimate friendship" with Lord Mandelson.
Writing in the Guardian, Mr Streeting said he was "not a close friend of Peter Mandelson", and met the peer "for dinner on average once a year, in a group setting".
He added that Lord Mandelson "offered advice".
He said he was "happy to have been proved wrong in terms of how I felt about the economy last year", citing growth and falling interest rates.
In another exchange Streeting asked for Mandelson’s views on formally recognising the state of Palestine, after France had done so, saying it would be politically impossible for him to vote against such a move in Parliament.
Mr Streeting wrote:"Morally and politically, I think we need to join France.
"Morally, because Israel is committing war crimes before our eyes. Their government talks the language of ethnic cleansing and I have met with our own medics out there who describe the most chilling and distressing scenes of calculated brutality against women and children.
"Politically, a Commons vote will be engineered in September on recognition and we will lose it if we're not ahead of it. There are no circumstances in which people like me or Shabana could abstain or vote against, for example. Conference will be a sea of Palestinian flags and the moderates will be waving them.
"We need to be leading the charge on this. The alternative is being dragged there with enormous damage to Keir, the govt and the party."
