A survey by ICM found that 40 per cent had confidence in the Conservative Chancellor and Prime Minister on the key issue, up from just 28 per cent in June, amid signs of a growing economic recovery.
Shadow chancellor Ed Balls and Labour leader Ed Miliband were well behind on 24 per cent, despite enjoying a five-point jump in their own rating over the same period.
The dramatic stretching of the gap came despite continued public pessimism about the prospects for personal finances, with more people expecting their situation to worsen (29 per cent) than improve (24 per cent) over the next year.
Labour has made the rising cost of living a key theme of its attack on the coalition’s handling of the economy.
Mr Miliband is under fire from some quarters within his own party for failing to set out sufficiently clear economic and other policies to attract voters and a “deafening silence” over the summer holiday period.
There was relatively better news for the opposition in the overall voting intention figures, which showed it regaining its recent slim lead over the Tories, who drew level last month. The latest poll put Labour down one point on 35 per cent while the Conservatives shed four points to stand at 32 per cent.
Most of those lost voters were picked up by the UK Independence Party, which gained three points to 10 per cent, with the Liberal Democrats gaining one point at 14 per cent.
Former Labour minister Chris Mullin said of the leadership: “I do think they need a strong, coherent case and they need a credible message.”
He continued: “Without doubt they have got a big hill to climb, especially now the economy is back into growth and an economic miracle is being declared – we are very far from an economic miracle, so it is not hard to counter.”
Mr Mullin said Labour should be attacking the “vast lie” that the previous government was responsible for the economic crash.
• ICM Research interviewed a random sample of 1,001 adults by telephone between 9 and 11 August.