The major northern cities that helped to build Britain are now failing to give many schoolchildren a decent education, Ofsted boss Sir Michael Wilshaw is warning.
Government plans to boost economic growth in the North - creating a so-called Northern Powerhouse - will "splutter and die" if more is not done to improve the performance of schools in the region, according to Sir Michael.
Manchester and Liverpool are the engines that could "transform" the prospects of the entire area, but currently, secondary education in these cities is not up to scratch, and may be getting worse, he suggests.
Ofsted figures show that three in 10 Manchester secondaries, and four in 10 of those in Liverpool are rated as less than good and that the proportion of teenagers gaining at least five C grades at GCSE - including English and maths, has dropped in both places.
In a speech to the IPPR think tank this morning, Sir Michael will say: "Yes, London has advantages that other cities lack, but what of Liverpool or Manchester?
"Are you really telling me that they lack swagger and dynamism? That they cannot succeed in the way London has succeeded?
"These are the cities that built Britain. They pioneered a modern, civic education when students at certain other universities spent most of their time studying the New Testament in Greek.
"Today, Manchester and Liverpool boast eight universities between them, two of which are among the top 200 in the world. They are beacons of higher educational excellence. But if these cities can provide a world-class education for youngsters at 18, why on earth are they failing to do so for too many at 11?
"At some point, we have to accept that our children's education can be better - or worse - because of the choices we make.
"At some point, politicians in Manchester and Liverpool will have to accept that the northern powerhouse will splutter and die if their youngsters lack the skills to sustain it."
He also argues: "Manchester and Liverpool are at the core of our ambitions for a Northern Powerhouse. They are the engines that could transform the prospects of the entire region.
"But as far as secondary education is concerned they are not firing on all cylinders. In fact, they seem to be going into reverse."
In his latest annual report, published in December, Sir Michael warned that England is "a nation divided at age 11", with a performance gap between schools in the North and Midlands and those in the South.
The chief schools inspector is calling for local politicians to take responsibility for their local schools and to challenge and support them to improve.
"I am calling on them to make education in general - and their under-performing secondary schools in particular - a central target of their strategy for growth," he says.
"Unless they do, I fear Manchester and Liverpool will never become the economic powerhouses we want them to be. We cannot fight for social mobility with political immobility.
"Politicians need to act. It requires grit, imagination, faith and bloody mindedness - qualities that, fortunately, I really don't think are less common in the North than they are down South."
Sir Michael's speech comes on the same day that Ofsted published an open letter to those responsible for education across Greater Manchester, which raises concerns that many pupils attending secondary schools in towns including Salford, Rochdale, Oldham and Manchester are not being properly prepared to go on to university, training or the workplace.
The letter, signed by Chris Russell, the watchdog's regional director for the North West, says: "This level of performance presents not only a worrying picture for the employment prospects of young people in one of the United Kingdom's major cities, it also presents a real risk to the economic and social stability of the area as a whole."