Anita Straker, director of the strategy, said she loses sleep over the best way of achieving the aim of 75 per cent of 11-year-olds reaching level 4 by 2002.
She told The TES: "My job is all-absorbing and all-consuming. I think we will make it but I do worry about ways the strategy can be improved." Mrs Straker revealed her fears to teachers this week at a TES-Keele seminar, one in a series for senior managers n schools and local authorities.
The target is one on which Education Secretary David Blunkett has staked his job.
Schools were required to teach a daily maths lesson from the beginning of the academic year.
The Government estimates that 70 per cent of primaries began teaching the national numeracy strategy a year ahead of schedule.
The next TES-Keele seminar will be on June 6 when Professor David Hopkins, of Nottingham University, will talk about school improvement strategies. More on this week's seminar can be found at www.tes.co.uk