The chances of Gordon Brown calling an autumn general election were disappearing fast last night as an exclusive poll for The Times showed that Labour is under pressure in the key marginal seats that it needs to win an election.

The Populus poll, undertaken over the weekend, also shows that the two main parties are now level-pegging, at 37 per cent for Labour, down two points compared with five weeks ago, and 36 per cent for the Tories, up three points. On these figures, Labour would have an overall Commons majority of about 20, compared with 69 at present. This indicates that a hung Parliament, with no party having a majority, is be a real possibility.

The poll will come as a relief to David Cameron, the Conservative leader, after a two-week blitz of speeches and activity designed to forestall an early election by puncturing the Brown bounce.

It also coincides with an attempt by Mr Brown and his ministers to dampen the daily speculation about an early election. The Prime Minister is expected to make a final decision about an autumn election within the next two weeks.

For the first time, Populus conducted an analysis of the 120 most marginal seats, half of which are held by Labour. This, based on the three monthly polls since Mr Brown became leader, shows the Tories doing better relative to Labour and the Liberal Democrats in the 60 most-marginal seats, many of which are in the South. The analysis of all 120 seats shows little difference from the national picture and underlines the risk of Mr Brown losing Labour’s majority.

The poll provides the clearest evidence to date that the big, six to nine-point Labour lead of early August has disappeared, after conflicting polls last week. Some correction after the Labour upsurge in July was to be expected, but Mr Cameron and senior Tories will be pleased that their counter-attack over crime, the NHS and Europe has boosted their ratings — and probably put off an early election.

Mr Cameron nevertheless came under attack from within last night when Michael Ancram, a former deputy Tory leader, told him to stop “trashing” the party’s Thatcherite past. “Claiming somehow to be the heirs of Blair in an attempt to recycle and benefit from New Labour’s past political successes risks merely relabelling yesterday’s rubbish,” Mr Ancram said.

Mr Cameron also has to contend with the news from the poll that the Brown bounce has not actually disappeared. Labour are still about five points above their rating before Mr Brown became Prime Minister and his leadership rating has improved and is still well ahead of Mr Cameron’s.

A problem for Mr Brown is that, while voters approve of his performance so far, only 6 per cent think he has made a real difference to Britain and nearly half (46 per cent) believe that he is all talk and no action.

The poll is mixed news for the Liberal Democrats. The three-point rise in their poll rating to 18 per cent partly reflects a change in the way the question was asked. But the party still faces the loss of many of its seats to the Tories, especially in the south.

In an interview on the BBC Radio 4 Today programme Mr Brown killed talk of an immediate announcement, while stopping short of ruling out a poll in the autumn. He said: “There will be no announcement today.There will be a time and a place for a general election, but it is not now.”

Asked to rule out an autumn poll, he said: “If there were to be an election, the first person I would tell is not you . . . it would be Her Majesty the Queen, and I have not done that.”

Some ministers have urged Mr Brown to take advantage of his strong start to get an election out of the way soon. The Labour machine is ready to give the Prime Minister the option to go to the country early if he so wishes.

— Populus interviewed a random sample of 1,506 adults aged over 18 by telephone between August 31 and September 2. Interviews were conducted across the country and the results have been weighted to be representative of all adults. Populus is a member of the British Polling Council and abides by its rules. Details at www.populus.co.uk.

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