Dorset Police and Devon & Cornwall Police have today announced plans to develop a 'closer relationship' between the two forces.
One of the options being considered is a full merger between the two forces into one force.
This follows a four-year programme between the forces that the forces say has led to more efficient work.
A consultation with stakeholders, local MPs and councils, on all the options being explored, are set to begin in the next few weeks.
If approved by the Home Office, the possible merger would be the first of its kind since 1974, creating the fifth biggest police force in the country in terms of numbers.
The Police Federation, representing rank and file officers, says it backs the merger so long it doesn't mean a cut in existing police numbers across the three counties.
The federation say any savings made by cuts to administration and back-office work should be put into front line policing.
Devon and Cornwall Police Chief, Shaun Sawyer, says the change is not merely being proposed to save money.
Shared leadership has already taken place across both forces.
The two deputy chief constables share portfolio areas and there are directors and heads of department who lead some areas across both forces. The three counties also share a number of services including administration, IT and HR.
Dorset Police chief constable Debbie Simpson says that the forces are already working closely together through a 'strategic alliance'.
She says a merger is a natural extension of that work and will benefit the public.
Although policing a wider area could present extra challenges, both chief constables say their forces are up to the task.
Another issue to be considered should the merger go ahead, would be the cost on council tax for the combined force.
At the moment, tax payers in Dorset in an average Band D property pay nearly £20 a year more for their policing than householders in Devon and Cornwall.
If approved, plans for the new force could be in place by 2020, when the next elections for police and crime commissioners are set to take place.