Cabinet Office minister Ed Miliband has started work on Labour's manifesto for the next general election.
Ed Miliband began work on the manifesto on Saturday
Downing Street sources told the BBC Mr Miliband has been asked to prepare a draft document ahead of the party's annual conference in September.
He was given the role when he was first promoted to cabinet last month, but began the task "actively" on Saturday.
Meanwhile, an ICM poll for the Sunday Telegraph found Labour had its biggest lead over the Tories for two years.
A spokesman said Mr Miliband's task, which he started at a meeting of Labour's national policy forum, would now go ahead "quite intensely".
The news will increase speculation that Prime Minister Gordon Brown is thinking of calling an early election, according to BBC correspondent Guto Harri.
Mr Brown has been encouraged by polls, including ICM's.
It gave Labour a seven-point lead, putting them on 40% compared to the Conservatives on 33% and the Lib Dems on 19%.
Poll findings such as ICM's would be enough to give Mr Brown a majority of more than 100 seats.
The ICM poll showed some support for Tory leader David Cameron's ideas, suggesting strong backing for his stance on the importance of marriage.
Some 70% of voters felt it was better for parents to be married.
ICM Research interviewed a random sample of 1,003 adults by telephone on 11 to 13 July.