Home Secretary Charles Clarke looks set to drive through a merger of the police forces in Wales.
Mr Clarke says a merger is the best way to police Wales
Mr Clarke had given the four Welsh police authorities until Friday to agree to a voluntary merger - but all of them have now rejected the plans.
Geraint Price-Thomas, who chairs the Gwent authority and the all-Wales authority has said the pace of reform is causing the greatest concern.
But Mr Clarke has said a single force is the best way to police Wales.
The Gwent authority was the last in Wales to formally reject the voluntary merger at a meeting on Thursday.
All four authorities are concerned about funding, community policing and the speed of change.
On 1 March the home secretary is expected to start the legislative procedure to force the merger through, which will start a four-month consultation period.
Mr Price-Thomas said he would keep talking to the UK government through this period but felt the position had to be made clear.
He said: "I think from time to time one has to make a stand and I'd be the first the first to acknowledge that in law, the home secretary does have the power of now to deliver to forced merger of the four welsh forces.
"Having said that, we consider that it's important from a local democratic perspective and from the point of view of our local communities that we do put a balance in and effect a reform that will be successful.
The UK Government says Welsh forces are currently too small
"We only want to restructure once and we only want to go through this process once."
Ray Thomas, chairman of South Wales Police Authority, said the "letter was in the post" to Mr Clarke explaining that organisation needed more detail about the financial implication of any change.
He said the authority was not opposed to the merger in principle, but added: "Certainly we're not going down the voluntary route at this time. We need the financial part in place first."
But Malcolm King, a member and former chairman of North Wales Police Authority, said his authority's concerns were more than just financial ones.
He said the HMIC report which recommended the merger had been "very heavily criticised".
Mr King added: "I think most people think it's a pretty half-baked report that has been sold to the home secretary and he's rushed in and reached much too early conclusions from it and now he's stuck with it".
Mr Clarke has said that a single force was the only way to police Wales adequately, by creating a force that would be large enough to best deal with the threats such as terrorism, drugs and organised crime.