Bob Sleigh, leader of Solihull council, said he intended to seek its approval for talks in principle.
The councils controlling Birmingham, Walsall, Sandwell, Wolverhampton, Coventry and Dudley have backed the combined authority proposal.
Cities may be in line for new housing, transport, planning and policing powers if they sign up for devolution plans.
Chancellor George Osborne said on Thursday that Greater Manchester should become a blueprint for other large cities.
There, leaders of 10 councils work together as part of combined authority and there are plans to elect a mayor for the entire area in two years.
Labour claimed the government's "piecemeal approach" could mask big cuts to local councils' spending.
On 14 July Solihull's full council will debate the plan to join other West Midlands authorities in talks over a proposed combined authority.
Mr Sleigh said he told full council he intended to seek approval "for taking forward detailed discussions in principle" to support a combined authority.
He said to achieve Solihull's ambition for sustainable economic growth, the borough "needs a high-performing regional platform of a scale and geography that attracts the significant inward investment needed to satisfy that ambition".
Council leaders have previously said the combined authority, which could serve four million people, would help attract investment worth hundreds of millions of pounds.
Solihull has moved closer to joining the proposal for a West Midlands combined authority.