The Welsh Secretary Peter Hain has said he still hopes that Wales' four police authorities will agree to voluntarily form one Welsh force this week.
Mr Hain was speaking ahead of the Friday deadline set by the home secretary for them to agree to merge.
He told BBC Wales' Politics Show that an early agreement for an all-Wales force would be the best way of securing the best possible financial deal.
But some police authority chiefs believe a deal by Friday is unlikely.
Mr Hain stressed the need for safeguards in respect of local accountability in merger negotiations.
He said that this was particularly important in respect of North Wales, where he hoped a deputy constable would be appointed.
"I want Wales to be among the four lead areas into this merger and make sure we get the best possible deal for resources, in some of the up-front costs", he said.
He said that the total package would ensure Welsh policing would be in a position to deal with terrorism, drugs and organised crime, as well as having the ability to react to major investigations, which stretched the resources of smaller forces.
"In terms of neighbourhood policing, it will be best protected under this merger," he added.
However, the police shake-up plans still face stiff opposition.
Police authorities want more money to bring in changes and assurances about local policing.
North Wales Police Authority last Friday voted against the plans and its chief constable Richard Brunstrom told members they would be "crackers" to agree.
Don Evans, the chairman of Dyfed-Powys police authority said he believed it would be "very unlikely" that it would agree to a voluntary merger at a meeting on Monday.
"We're concerned our resources will be moved to the busier areas and affect our local policing and we don't want that to happen".
Geraint Price-Thomas, chairman Gwent Police Authority also believed a voluntary deal was unlikely by Friday but said they had to secure the best police service and best financial deal for council tax payers.
Richard Eccles, chairman of North Wales Police Federation, said he believed the threat of terrorism was being used to drive the merger and raise concerns with the public.
"This is more about reforming and restructuring forces for future economies than the threat to national or even local security".