The findings of the first opinion poll of the year suggested that the main opposition Conservative Party leader, David Cameron, had overtaken Brown on the qualities required to be prime minister for the first time.
The Populus poll of 1,509 adults on January 4-6 indicated Cameron was more likeable, more honest and charismatic than the Labour Party leader, plus understood and had the answers to the country's big problems.
Some 44 per cent also said Cameron has what it takes to be premier -- up four points on the last similar survey on July 27-29. Brown was on 40 per cent, down nine per cent.
Brown's personal rating on a scale of zero to 10 also slumped to 4.6 from a high of 5.49 one month after taking over from Tony Blair in June last year. Cameron was up to 5.07.
Overall, support for the three main parties was Conservatives 37 per cent; Labour 33 per cent; and the smaller Liberal Democrats on 19 per cent.
Brown, who was still seen as stronger than Cameron, on Monday announced plans for a new national screening programme for public health sector patients in England to combat some of the country's biggest killer diseases.
He also appointed the former head of the media industry regulator Ofcom, Stephen Carter, to lead his political and strategic team and has toured television and radio studios to show he was back on track after recent woes.
A key announcement on a possible new generation of nuclear power stations is expected later this week.