One in three Labour voters thinks Ed Miliband should not lead the party into the next general election, according to a new poll.
The survey also found that only two out of every 10 voters are satisfied with the Labour leader's performance.
Some 34% of people who voted for the Labour Party in 2010 say he should not lead the party into the 2015 general election, while just 46% say he should, according to the ICM poll carried out for the Daily Mirror.
While 21% of voters said they are satisfied with the way he is leading the party, double the number (42%) said they are dissatisfied. Among Labour voters, 45% said they were satisfied and 31% dissatisfied.
Mr Miliband will find it harder to dismiss criticism of his management style following publication of the poll by the left-leaning tabloid, which has traditionally backed his party.
His summer leadership crisis has not been helped by criticism from within his own ranks that the Opposition has failed to stop the Conservative Party from dominating the news agenda.
Mr Miliband's approval rating is particularly low among older and male voters. Of those polled, 61% of pensioners said they are unhappy with his leadership, while 48% of men say he is not up to the job, compared with 37% of women.
However, the poll offers Mr Miliband a few glimmers of hope.
Given a choice of eight Labour MPs, Ed Miliband came out on top with 16% when asked who would be the best person to lead the party. Among Labour voters, this figure was 28%, 10% ahead of his brother David Miliband.
Mr Miliband also comes out on top when voters are asked about which of the party leaders are more likely to be in touch with the rest of society, help the poor and be honest.