Labour leader Jeremy Corbyn has backed a devolution deal involving the whole of Yorkshire.
Speaking at a meeting in Huddersfield on Saturday, Mr Corbyn said he hoped all the councils were "working together" on the deal.
"There is I think a growing consensus of pretty well all of the local authorities in Yorkshire that a One Yorkshire way forward is a good thing to look forward to," he said.
A deal for the Sheffield City Region was agreed in 2015 and mayoral elections are due to take place in May at a cost of £1.9m, but the leaders of Barnsley and Doncaster Councils are among those supporting the 'One Yorkshire' bid.
They have previously called for the forthcoming election to be postponed or for the mayoral term to be limited to two years.
On receiving the 'One Yorkshire' proposal last month, the government said: "We have always said that we would welcome discussions on any widely supported proposal for a greater Yorkshire devolution deal provided the Sheffield City Region deal was not threatened and the proposal clearly relates to a sensible economic geography."