Andy Burnham’s popularity has taken a sharp 20-point hit after increased contact with voters, according to the latest YouGov poll.
The Mayor of Greater Manchester, who is standing in next week’s Makerfield by-election, now holds a net approval rating of minus 11, down from a previous high of plus nine.
Four in 10 Britons now view him negatively, while only three in 10 hold a favourable opinion.
The 20-point drop began in mid-May, shortly after the local elections triggered growing tensions within the Labour Party.
Josh Simons stepped down from his Makerfield seat, opening the door for Mr Burnham to make a return to Westminster through a by-election.
YouGov said: “In earlier polls, Andy Burnham recorded a positive net favourability rating, peaking at +9.
“However, his ratings began to fall from mid-May — a period that coincided with Labour’s internal revolt against Keir Starmer, including Wes Streeting’s resignation and Josh Simons stepping down in Makerfield, triggering the by-election Burnham is widely expected to win.
“As a result, Burnham now sits on a net favourability rating of -11 in our latest poll, with 30 per cent of Britons viewing the would-be PM positively, compared with 41 per cent who view him negatively.”
Research from More in Common shows only 16 per cent of the public trust Mr Burnham on defence — the same rating as Sir Keir.
Nearly half of those surveyed said they trust neither leader, while another fifth were undecided.
Only one in five believe the UK could defend itself against an attack on home soil, and just 12 per cent are confident in Britain’s ability to carry out overseas military operations.
Around two-thirds also doubt the country could withstand aggression from either Russia or China.
In head-to-head polling, Ipsos found Mr Burnham leads Keir Starmer by 13 points (25 per cent to 12 per cent) on who would make the better Prime Minister.
The poll also found that 50 per cent of the public answered “neither” or “no difference” when asked who would be the stronger leader.
Surveys of Labour members and 2024 voters continue to show Burnham as the clear favourite to take over the party if Mr Starmer steps down following a wave of senior resignations.
Sir Keir Starmer has insisted he will fight any future leadership challenge, saying he will not step aside and that his decision to remain is driven by a “deep sense of duty.”
Wes Streeting resigned as Health Secretary on May 14, saying he no longer had confidence in the Prime Minister’s leadership.
Just last week, John Healey resigned as Defence Secretary after clashing with the Treasury over the Defence Investment Plan.
More than half of Britons (52 per cent) believe the Government should increase defence spending, including nearly two-thirds (63 per cent) of Labour voters.
According to More in Common, the public is twice as likely to say John Healey was right to resign (46 per cent) than wrong (23 per cent).
