Gordon Brown still has some way to go in persuading voters that he would be a good prime minister, according to a new opinion poll.
An ICM poll for The Guardian finds the Conservatives continue to lead Labour in popular support and this lead would only increase if the chancellor was in No 10.
If there was a general election tomorrow and Tony Blair was still leader, 32 per cent of voters would choose Labour, compared to 37 per cent for David Cameron's Tories.
However, if Mr Brown was leader, although Labour would keep their support, the Tories would surge ahead to 40 per cent - the margin that is considered enough to win power.
The Liberal Democrats would be the ones who were squeezed - although they remain steady on 22 per cent of support if faced with Mr Blair, this would drop to 20 per cent if the contest were between Mr Cameron, Mr Brown and their leader, Menzies Campbell.
Today's poll is not good news for Mr Brown, who has recently tried to increase his appeal to voters by discussing issues beyond his normal Treasury brief.
He was boosted by the apparent endorsement of the prime minister during the Queen's speech debate last week, when Mr Blair warned the Tories would be facing a "heavyweight" at the next election. But this apparently is not enough for voters.
However, Labour has recovered from a record low in last month's ICM poll, which put the party at just 29 per cent of support. This suggests efforts to present a unified front after the infighting of September are making a difference with the electorate.
On Monday, Tory advertising guru and former party chairman Lord Saatchi warned that in moving to the centre ground, Mr Cameron risked alienating voters. But reports suggest he will ignore this advice and use a lecture on Friday to signal further changes.
In the Scarman lecture, the Tory leader is expected to call for a review of the party's welfare policies, arguing that the old idea of the welfare state being simply a safety net to keep people above the breadline is insufficient.