A leading political thinktank h as backed calls for a directly-elected mayor in Birmingham as the key to city region status.
The Institute for Public Policy Research believes the additional powers conferred yesterday on Ken Livingstone, the mayor of London, shows that the Government is determined to move towards the mayoral model.
IPPR researcher Dr Adam Marshall said it was clear that council leaders in cities such as Birmingham, Manchester and Liverpool did not want all-powerful elected mayors, but they might be forced to change their minds.
A White Paper to be published later this year will set out the Government's thinking on city regions and mayors.
Dr Marshall said: "If Whitehall offers a substantial package of powers to a big city or a city region and says you can have these if you have a mayor, I think some cities would be hard-pressed to refuse."
The IPPR, which is sometimes described as Labour's favourite thinktank, believes Local Government Secretary Ruth Kelly is determined to succeed where her predecessors have failed by introducing elected mayors in most major UK cities.
Dr Marshall said: "The best form of leadership that she can imagine is directly elected mayors. She has challenged city regions to come up with a better alternative.
"But she has given a clear steer that elected mayors are her preferred model.
"This has obvious ramifications for the White Paper and has a clear message for the likes of Birmingham, Manchester, Liverpool and other city regions.
"Whitehall has the confidence to devolve more and more power to a directly elected mayor in London. If one of our other big cities went for a similar model I can see powers being devolved in the same way as has happened in London."
He said it was unclear whether the Government would force councils and city regions to have mayors.
Ministers have said they are not convinced that executive boards comprising council leaders, of the type being suggested for Birmingham and the West Midlands, are the most efficient way to run city regions.
Dr Marshall added: "Council leaders in Birmingham and Manchester don't want a mayor. But I don't think the Government is convinced about an executive board model. They want a stronger mechanism.
"You can sympathise with local government leaders. They are working at a very difficult job and they find themselves reorganised regularly. It is understandable that they are wary of yet more change."
Dr Marshall expects large city councils, like Birmingham and Manchester, to look enviously at the budgets and executive powers enjoyed by Ken Livingstone.
He added: "We are talking about a very radical and growing set of powers that allows the mayor of London to really shape the capital's economy.
"He will have new powers over strategic planning, he will have the power to allocate the affordable housing budget, he is going to have a far bigger role in determining how training money is used.
"Having decisions made locally rather than by a one-size-fits-all Whitehall department makes a lot of sense."
A city leadership report published by the IPPR earlier in the year urged the Government to establish a Greater Birmingham Authority, with powers to tax and spend.