It was bad. It is now worse. If the Cabinet meeting that occurred yesterday had been scheduled for this morning instead, then ministers might well have decided to cancel it and sit weeping in the sunshine. The details of the latest Populus poll for The Times are devastating. The Conservatives today have the largest advantage that this polling company - less prone to some of the violent swings recorded by others - has produced in the past five years. Gordon Brown's personal rating has slumped to the lowest yet discerned for a prime minister. More than half of those consulted, including a majority of Labour supporters, believed that Labour's best option was to replace him with someone younger and more charismatic. The outcome of the Crewe & Nantwich by-election this month appears to be a foregone conclusion.

None of this will do anything for the mood inside the Parliamentary Labour Party. MPs are desperate to be able to take a solution to the abolition of the 10p tax band back to their constituents, but the complexity and cost of rectifying this self-inflicted error means that none can be delivered. David Cameron moved to exploit this yesterday, even though he could no more reverse this shift in policy than Mr Brown can. Labour is due for a torrid few months until the summer recess, and its poll ratings might easily get worse by then.

All of this is seismic compared with Labour's standing only two months ago. In March the Tories were but three points ahead and the smart money was on Ken Livingstone to be re-elected in London, not turfed out to make room for Boris Johnson. There has to be a dominant explanation for such a change in public sentiment. And there is. It's the economy, stupid.

Since last September Populus has asked voters regularly whom they would trust most to deal with economic difficulties; the Prime Minister and the Chancellor or Mr Cameron and George Osborne. In that time, the proportion favouring the Labour duo has halved from 61 per cent to 30 per cent while the Conservative alternative has seen backing rise from 27 per cent to 40 per cent. It is evident that the country is very worried about the economic outlook and has lost confidence in the Government's ability to conduct economic management in a competent manner.

In a strange way, this offers a kind of cheer for the Government. Mr Brown's plight is not quite as dire as was John Major's at the midpoint of the 1992-1997 Parliament. The fundamental problem for the Conservatives then was a sharp division over an issue (Europe) on which they found it impossible to find a viable compromise. It was not policy, as such, that undermined them. In this Prime Minister's case, he can cling to the hope that, were the economic slowdown to be milder than expected, he could stage a recovery.

The difficulty with this is that the character of current economic concerns are not of a form that unilateral activity from the Treasury can counter. Within the United Kingdom, power is shared with the Bank of England. Even if it were not, the credit crunch and its aftershocks are an international challenge. The restoration of Mr Brown's fortunes depends as much on a pronounced rebound in growth in America as on any other element. As a paradoxical result, Ben Bernanke, the Republican-appointed Chairman of the US Federal Reserve Board finds himself the de facto campaign manager for the British Labour Party's 2010 bid for a fourth term effort.