WIRRAL Labour and Liberal Democrat councillors united in favour of the borough becoming part of a combined Merseyside authority.
During a heated meeting at Wallasey Town Hall, the move was approved 42 to 19 in support of leader Phil Davies' proposal to join the region's five other authorities.
The combined authority will be established on April 1. Its creation puts the new body in line for a share of a £2bn "single growth pot" the Government had made available over the next five years in England.
An amendment by Hoylake Conservative councillor John Hale called on the council to consider a holding a referendum before a final decision was made. But it was defeated by the same 42-to-19 margin.
Councillor Hale said: "With the proposed new council there will be six council leaders.
"Five of these will feature people who will not be representative of Wirral, or will be living in Wirral.
"It is the absolute antithesis to democracy. I don't think it's incumbent on anybody to transfer these powers to another body. I think there is a need for a referendum."
But Cllr Davies said it was vital the region takes the step: "To somehow suggest this is an idea generated by Wirral Labour group is utter nonsense.
"The idea of combined authorities was formed by the Conservative and Lib Dem coalition.
"We've heard a lot of waffle that this will operate another level of bureaucracy. Absolutely not. It makes so much sense to have a combined authority."
Liberal Democrat leader Cllr Phil Gilchrist agreed, saying: "We'd be shooting ourselves in the foot if we don't take part in this organisation."