An opinion poll this evening shows the Labour Party's lead over the Conservatives in Britain has fallen 7 points in just a week.
The Conservatives have been boosted by their annual conference this week where party leader David Cameron promised a tax break for people buying their first home and a cut in inheritance tax.
The YouGov poll for Channel 4 television showed Labour on 40 percent to the Conservatives' 36. Some 1,741 people surveyed yesterday and today.
An opinion poll in tomorrow's Guardiannewspaper is also expected to show a sharp drop in Labour's lead, and will give Prime Minister Gordon Brown pause for thought as he decides in the next few days whether to call a snap election.
A 4-point poll lead would make Mr Brown's goal of increasing the 64-seat parliamentary majority Labour won at the 2005 election difficult, said John Curtice, politics professor at Strathclyde University.
"It definitely means we are still on tenterhooks," he said.
Channel 4 said several Labour MPs in marginal seats were urging Mr Brown to delay an election. Government officials have made plans to bring forward major announcements, including public spending plans, to early next week in case Mr Brown decides to announce next Tuesday that he is calling a November 1st election.
Since taking over from Tony Blair in June, Mr Brown has impressed voters with his handling of crises ranging from attempted bombings to floods.
His strong poll numbers led him to consider calling an early election two-and-a-half years early, securing his own mandate to govern.