Sir Keir Starmer faces renewed scrutiny over his decision-making as it emerges that senior Cabinet member David Lammy cautioned against appointing Lord Mandelson.

Reports suggest that both Mr. Lammy and Jonathan Powell, the national security adviser, advised the Prime Minister against nominating the peer for the role of Britain’s ambassador to the U.S.

At the time, Mr. Lammy, then serving as foreign secretary, reportedly preferred to see Dame Karen Pierce continue in her position as the UK’s leading diplomat in Washington, DC.

Currently, Sir Keir is grappling with a significant crisis in his 18-month tenure, spurred by recent revelations regarding Lord Mandelson’s association with Jeffrey Epstein.

The Prime Minister has publicly expressed regret, admitting he was misled by Mandelson’s falsehoods concerning the peer’s connections to the disgraced financier when he appointed him in February 2025.

In the wake of the scandal that has overtaken his administration, numerous Labour MPs are vocally questioning Sir Keir’s ability to maintain his position at Downing Street.

New polling has revealed a fresh slump in the PM’s approval ratings, while more than half of voters said Sir Keir should quit.

Angela Rayner, the former deputy PM who is also said to have warned Sir Keir against appointing Lord Mandelson, is being widely touted as a possible successor.

Sir Keir Starmeris facing fresh questions over his judgement as it was revealed senior Cabinet minister David Lammy warned him not to appoint Lord Mandelson

Mr Lammy – who was foreign secretaryat the time – is reported to have favoured extending Dame Karen Pierce’s term as the UK’s top diplomat in Washington DC

Health Secretary Wes Streeting, Energy Secretary Ed Miliband, Armed Forces minister Al Carns and Labour deputy leader Lucy Powell are also seen as potential candidates.

But Greater Manchester mayor Andy Burnham now appears to have only a slim prospect of fulfilling his leadership ambitions, after he was blocked from standing in the Gorton and Denton by-election by Sir Keir’s allies.

An Opinium poll found 55 per cent of the public think Sir Keir should resign, with only a quarter (23 per cent) believing he should remain in post.

Meanwhile, the PM’s approval ratings remain very low with just 17 per cent approving of Sir Keir’s performance – compared to 61 per cent who disapprove.

This gives the PM an overall approval rating of -44, down three points from Opinium’s previous survey.

It means Sir Keir is more unpopular than all the other major party leaders, including Tory chief Kemi Badenoch (-9), Reform UK’s Nigel Farage (-11), Liberal Democrat leader Sir Ed Davey (-3), and the Green’s Zack Polanski (-3).

A majority of the public (56 per cent) believe Sir Keir should have anticipated the controversy before appointing Lord Mandelson as US ambassador and should not have appointed him.

Only 15 per cent believe the decision was reasonable based on what was known at the time.

James Crouch, head of policy and public affairs at Opinium, said: ‘The deepening fallout from the Mandelson appointment has pushed Starmer’s rating even lower, with most voters now questioning his judgement on the appointment and placing equal blame on the prime minister and his advisers.’

The Sunday Times reported that both Mr Lammy and Mr Powell had warned Sir Keir not to appoint Lord Mandelson as US ambassador in February 2025.

It has also been revealed that Lord Mandelson received a five-figure payout when he was sacked from the role in September last year.

The peer is now facing demands to hand back the taxpayer-funded severance payment.

Allies of Prime Minister Sir Keir said the peer should return the cash or donate it to a victims’ charity.

The Foreign Office said a review had been launched ‘in light of further information that has now been revealed’.

Angela Rayner, the former deputy PM who is also said to have warned Sir Keir against appointing Lord Mandelson, is being widely touted as a possible successor

A spokesman said: ‘Peter Mandelson’s civil service employment was terminated in September 2025 in accordance with legal advice and the terms and conditions of his employment.

‘As we have consistently said to Parliament, normal civil service HR processes were followed.

‘Further information will be provided to Parliament as part of the Government response to the motion passed last week which is being co-ordinated by Cabinet Office.

‘A review has been instigated in light of further information that has now been revealed and the ongoing police investigation.’

The Metropolitan Police said its investigation into Lord Mandelson, 72, over alleged misconduct in public office would ‘take some time’ after officers finished searching his homes in London and Wiltshire.

‘This will be a complex investigation requiring a significant amount of further evidence gathering and analysis,’ Metropolitan Police Deputy Assistant Commissioner Hayley Sewart said.

A spokesman for Mr Lammy, who is now Justice Secretary and Deputy PM, said: ‘The Deputy Prime Minister is focused on the job in hand and fully supports the Prime Minister as he gets on with delivering for the British people.’

Lord Mandelson has denied the so-called ‘Epstein files’ show he broke any laws or acted for personal gain. He has repeatedly said he regrets his friendship with Epstein.

Opinium surveyed 2,054 adults between Wednesday and Friday.