By politics.co.uk staff
The Liberal Democrats' flagship policy for disadvantaged children is failing, according to an official report.
The embarrassing development comes as Nick Clegg faces mockery and criticism for a video apology in which he tried to move on his broken promise over tuition fees.
A report from Ofsted out today found the Liberal Democrats' flagship pupil premium policy is only partially succeeding, as schools used the extra cash to offset other spending cuts.
The regulator's survey found that half of schools thought the premium made little or no difference to the way they work.
The report is particularly badly timed for the Lib Dems, who argued this morning that they sacrificed policies like tuition fees in order to secure items such as the pupil premium in the coalition negotiations.
Instead of putting in place new activity, schools were disaggregating the pupil premium from their main budget.
"We want to see schools use the pupil premium far more effectively," children's minister David Laws told the Today programme.
"Around half the schools do believe the pupil premium has had a beneficial impact of some kind."
Over two-fifths of school leaders said the pupil premium money was being used to pay for more teaching assistants, however.
These could target disadvantaged pupils by providing more one-on-one tuition, but there is little concrete evidence they are doing so.
As of this month schools are required to publish information about how they have spent the pupil premium money online.
This "accountability mechanism", as Laws described it, will "hold schools to account" and help "spread best practice".
Overall the coalition is spending £1.25 billion on the pupil premium, which Lib Dems have trumpeted as one of their biggest achievements since entering government.
The Department for Education said it was unacceptable that children from disadvantaged backgrounds are less likely to do well in school than their peers.
"The coalition government has introduced the pupil premium to tackle this problem," a spokesperson said.
"We have given schools the freedom to use the additional funding in innovative ways.
"However, it is vital they use it to boost results for the most disadvantaged pupils, drawing on the large amount of evidence on how to make the biggest difference."