A Tory government would make 11-year-olds resit maths and English tests in primary schools if they fail to pass them the first time around, David Cameron will announce today.
The prime minister will say that the children will have to take the examinations in the first year of secondary school.
Official figures show that the resit policy, which would come into force from September 2016, could after around 100,000 pupils who fail to meet adequate levels of literacy and maths skills.
"These past five years we have been about getting changes in place which stretch our children – and the results have been extraordinary. The next five will be about finishing the job," Cameron will say.
"There is no job that doesn't require English and Maths and this is about making sure every child gets the best start in life and that our country can compete in the world."
The Tory leader will be accompanies by the Education Secretary Nicky Morgan, who will also make a speech.
"We know that the biggest predictor of success at GCSE is whether young people have mastered the basics at age 11," she is expected to say.
"That means if we fail to get it right for young people at the start of secondary school they'll struggle for the rest of their time in education.
"Under Labour one in three children left primary school unable to read, write and add up properly, thanks to our reforms and teachers' hard work we've seen that fall just to one in five. But even one child falling behind, or being written off, is a child too many."
Tristram Hunt, Labour's shadow education secretary, claimed the manifesto commitment was "a desperate attempt" to distract from the government's "failures on school standards".
"On their watch, 1.6 million pupils are being educated in schools that are rated lower than 'good' by Ofsted. And as a result of Cameron's unqualified teachers policy, more than 400,000 pupils are being taught by unqualified teachers," he argued.
"Labour has a better plan for education. We will ensure that every teacher is qualified or working towards qualified teacher status and introduce a new Master Teacher status to raise the standing of the profession. That is how we improve education for every child, in every classroom."
The announcement comes with 29 days to go before the general election, with Labour two points ahead of the Tories (35% vs 33%) in the latest opinion poll from YouGov.