Harriet Harman has been taking soundings from Labour activists over Gordon Brown's performance as signs grow that the Prime Minister faces a fresh leadership crisis.
Local party officials are being regularly canvassed by the party's Deputy Leader for their opinion over the Government's direction and Mr Brown's success in putting across its message.
It came as senior union leaders meeting at the TUC conference in Liverpool called on their members to rally behind Mr Brown, despite urging the Prime Minister to change his party from being a "soft Tory option".
Ms Harman's actions will be seen by some Labour MPs as positioning for a possible bid to succeed Mr Brown. Her team is asking constituency officers who is the "best person to sell the Labour Party" and to rank the performance both of the Prime Minister and herself on a scale of 0 to 5.
It comes as Mr Brown enters a perilous autumn, with his internal enemies threatening to make one last attempt to remove him from office if Labour's poll ratings do not recover by the end of the year.
Last night a spokeswoman for Ms Harman denied there was any sinister motive for the canvassing, adding that it had been taking place since she became Deputy Leader in 2007. She said: "Harriet has a team of volunteer activists who regularly call constituency Labour parties to get their opinions and ask them to raise issues. She has always seen it as an important way of connecting with the grass roots."
The group of union leaders, which included some that had attended a meeting with the Prime Minister at Chequers on Friday, said that members needed to put their weight behind Labour to avoid a Tory landslide at the next election.
Derek Simpson, joint secretary general of Unite, admitted that some of his members might not understand why he was backing the Labour Government, but said unions had to "wake up and smell the coffee".
He said any talk of withdrawing funding or setting up rival parties to Labour should be ditched immediately. "I think you have to be blind, deaf and dumb not to see Labour is in a great deal of trouble," he said. "Let's get real. We've all got these passions, we all want more to be done to protect jobs, to protect houses, to protect pensions, to stop privatising the health service, to keep the Post Office public. But a Tory government will do nothing for us at all."
However, though he said the party did not need a new leader, he criticised Mr Brown's approach and demanded major changes "in policy, attitude and approach". He added: "We want a government that looks like it's not terrorised by the idea of doing something constructive, that might actually be called socialism. We want a government that will come out clearly, telling all those millions of voters that we've lost, that they're on their side, that they're not the government of big business; that they're not the soft Tory option as so very often, they seem to be."
Billy Hayes, general secretary of the Communication Workers Union (CWU), admitted the relationship with Labour was "at breaking point", but said unions should remain affiliated and fight to change the party. "There might only be 6 per cent difference between Labour and the Tory party, but we have to live and fight in that 6 per cent. We have to deal with reality."
* Nearly half of voters believe any Labour figure could do a better job than Gordon Brown, according to a Populus poll for The Times. “Literally anyone” from within the party would be an improvement, said 48 per cent of those polled. However, only 17 per cent could name a better alternative.Reuse content