Pupils who fail to achieve good passes in English and maths at the age of 11 will have to re-sit their exams under Conservative plans to help students who fall behind catch up.
The proposals would see pupils sitting their tests again in their first year of secondary school, in a bid to ensure that those who leave primary school unable to read, write or add up properly will have caught up by the time they are 12.
Labour has hit back at the plans, claiming the scheme was an attempt to disguise the Tories' "failures" on school standards.
Education Secretary Nicky Morgan said the numbers of children leaving primary school without basic English and maths skills had fallen from a third in 2009 to a fifth - but with 100,000 still slipping through the net, she said, there was still more to be done.
According to government statistics, only seven per cent of those students go on to get at least five good GCSEs including English and maths - vastly below the average for the general school population of 72 per cent.
David Cameron said the plans were "about making sure every child gets the best start in life", as there is "no job" which does not require English and maths.
Improving these basic skills, he added, would help ensure Britain could continue to "compete in the world".
But Labour's shadow education secretary, Tristram Hunt, accused the Conservatives of making a "desperate attempt to try to overshadow their failures on school standards."