John Stannard, director of the National Literacy Strategy, told academics that the target - 80 per cent of 11-year-olds reaching the level expected for their age by 2002 - was giving him sleepless nights. Last summer, 64 per cent reached the literacy target in national tests.
Speaking this week at a literacy conference in Southampton University, he said it would be "an astonishing thing" if the target was reached, given current results. "I wouldn't predict 80 per cent in 2002 at this stage. The critical point is 2000. If education authorities still have 10 percentage points to make up at that stage, it is going to be a mountain to climb."
But if the 2000 results are good, the strategy will be "on a roll", he added. "I'm leading the strategy and I go for broke. We should be tolerating no less than 80 per cent by 2002. It's when you go to schools and talk to heads about individual children and the prospects of those children getting there that you start to worry."
The Government is investing pound;20 million in additional classroom assistants this year, to support literacy and numeracy work. Mr Stannard said the money, distributed to education authorities via the standards fund, would be used to support phonics, guided reading and sentence level work with current Year 3 and 4 pupils - the children who take their national tests in 2002.
But there are also plans for a Reading Recovery-style follow-up programme of additional support for children whose reading has failed to take off after a year of literacy hour teaching, he said.
The need for additional support for some Year 1 pupils was suggested in a review of research and related evidence underpinning the national literacy strategy, commissioned by the Government.
Its author, Dr Roger Beard, of Leeds University, notes that literacy programmes in the US and Australia include such "second wave" support for an expected 18 per cent of struggling readers. A further 2 per cent might need further referral and special support.
"Very little evidence exists for the success of programmes designed to correct reading problems beyond the second year of schooling," said Dr Beard.