Ministers have piled more pressure onto West Midlands council leaders planning a new combined authority by telling them bluntly they must have a mayor to win significant new powers and funding.
But it has emerged the seven councils behind the planned West Midlands Combined Authority have drawn up proposals for a system without any clear leader at all.
Instead, each local council leader is to take on responsibility for a "portfolio" such as transport or economic development.
Plans for a West Midlands Combined Authority, to include Birmingham, Solihull, Coventry, Wolverhampton, Dudley, Walsall and Sandwell, were published last week following months of negotiation and welcomed by Chancellor George Osborne in his Budget statement to the House of Commons.
The aim is to take responsibility for issues like public transport and skills and to set up a fund for investment in major regeneration schemes.
Greater Manchester councils have already set up a combined authority, led by a mayor, and agreed a major package of funding and devolved powers in central government.
But speaking in a Commons debate, Local Government Minister Marcus Jones made it clear the West Midlands would also need a mayor if it wanted a similar deal.
He said: "It is clear that, if the West Midlands wants to put together a package as extensive as Manchester's, for example, it will certainly need a metro mayor."
Ministers insist they are not forcing any area to create a mayor because combined authorities are free to make do with a less ambitious devolution package.
Mr Jones said: "As the Chancellor has made clear, we will devolve major powers only to cities that choose to have an elected metro mayor but the Chancellor has also made it clear that we will not impose a metro mayor on anyone."
He added: "Where there is a request for the ambitious devolution of a suite of powers to a combined authority, there must be a metro mayor, but no city will be forced to take on those powers or to have a metro mayor, just as no county will be forced to make any governance changes."
A spokeswoman for the West Midlands Combined Authority said the plan was to have a system of "distributed leadership".
She said: "In recent discussions, it's been decided the different (local council) chief executives lead on different portfolios as do leaders."
It would mean the leader of Birmingham City Council taking responsibility for one policy area, such as skills, transport or perhaps economic development, while the leader of Solihull Council led on a different area and so on.
Birmingham MP Gisela Stuart (Lab Edgbaston) said she feared the arrangements would lead to a lack of real leadership.
She said: "If you simply have rotation of portfolio holders, you are missing a key element of what real devolution means."
The Government's insistence on creating a mayor was criticised by Jim Cunningham MP (Lab Coventry South).
Speaking in the debate, he said: "The idea of an elected mayor is not new for the people of Coventry.
"On May 3, 2012, a referendum was held in which the people of Coventry voted decisively against an elected mayor. With nearly two thirds voting against, the idea was soundly rejected.
"Birmingham, which is also likely to join a West Midlands combined authority, voted against the same idea on the same day but those democratic decisions now look likely to be overruled without the people of Coventry, Birmingham or anywhere else being consulted."
Birmingham MP Liam Byrne (Lab Hodge Hill) said: "If there is to be any change in England's devolution arrangements, and ideas such as metro mayors are to be brought back to the table, surely those changes can come only with an absolute game-changer of an offer to devolve power from Westminster to different parts of the country."