A new poll has given the Conservative Party their lowest rating since the general election, as it gears up for its annual conference next week.

The Guardian/ICM poll is the second this week to give Labour a lead over the Tories. It puts Labour on 37 points, the Conservatives on 35, and the Liberal Democrats on 18.

This is a significant shift, and together with Wednesday's YouGov poll is the first time since Gordon Brown's election-that-never-was in 2007 that Labour have been ahead.

But while this is psychologically a major boost for the new Labour leader, Ed Miliband, it is worth noting that the party's lead is the result of Conservative support falling away, rather than a vote of confidence in the new leader. Labour's support remains unchanged from last month's ICM poll.

But it is certainly bad news for the Tories -- this is the lowest rating that any poll from any company has given them since the general election (the YouGov poll had them on 39 points), and comes several weeks before the full details of spending cuts have even been announced.

This slump in support is partially explained by some of the other findings in the poll. Public sentiment appears to be turning against the scale and speed of spending cuts; 43 per cent said that the cuts have gone too far, with 37 per cent feeling that the balance is right. This compares with July, when just 38 per cent said that cuts were going too far, and 39 per cent thought the balance was right.

The poll should bring some comfort to the Liberal Democrats, who gained just 13 points in the YouGov poll earlier this week. Indeed, the low showing for the Tories may well be related in part to the higher rating for Nick Clegg's party. ICM have consistently shown about 18 per cent support for the Lib Dems, while YouGov has given them ratings as low as 12 per cent.

While 50 per cent of people said that they still trusted the coalition the most to ensure a prosperous future for Britain (compared with 31 per cent for Labour), this does not bode well for support for the government after the comprehensive spending review on 25th October. Miliband would do well to tap into this growing discomfort, but he still has the task of convincing the public that he and his party would do better.