A powerful new cross-party campaign is threatening to derail Theresa May's plans to expand the number of grammar schools in England.
Former Conservative Education Secretary Nicky Morgan is joining forces with Lib Dem ex-Deputy PM Nick Clegg and Labour ex-shadow education minister Lucy Powell to oppose the proposals.
Mrs Morgan says the priority should be to make all schools good.
But Mrs May says her "personal mission" is to increase diversity in schools.
In a joint article in the Observer, Mrs Morgan, Mr Clegg and Ms Powell argue that creating new grammar schools will do nothing to promote social mobility - and warn there is no room for more "division or political ideology" in the education system.
Mrs Morgan, who was education secretary from 2014 until she was sacked by Mrs May when she became prime minister in 2016, said her experience had shown that the focus needs to be on schools in areas of the country where educational under performance is entrenched.
