Leigh MP Andy Burnham has urged the new Prime Minister to guarantee that plans for the Northern Powerhouse will proceed.
Speaking after Theresa May's committee on the economy and industrial strategy met for the first time, the shadow home secretary raised concerns that focus could be shifted away from reviving northern cities to a broader redistribution of the economy away from London and the South East.
Mr Burnham Warned scrapping the Northern Powerhouse scheme, which was created by former chancellor George Osborne, would be "the biggest betrayal of people in the North of England since Margaret Thatcher tore the heart out of many of its industrial communities in the 1980s".
Shortly after taking over as Prime Minister, Mrs May appointed Andrew Percy as Northern Powerhouse minister and the plans were described as a "key government priority" by the Government.
At the inaugural meeting of the new Cabinet committee on Tuesday, Mrs May stressed the Government should focus on delivering "an economy that works for all".
However Mr Burnham suggested the PM appeared to have "changed her tune" from earlier pledges to close the so-called North-South divide.
Mr Burnham said such a change in policy would increase a "crisis of confidence in our democracy" as the Northern Powerhouse would end up as "nothing more than meaningless spin".
He added that the possibility the plans were in jeopardy reinforced his candidacy to be elected mayor of Greater Manchester in May next year.