Police chiefs from six forces under pressure from the Home Office to find a way to amalgamate have decided to focus on three schemes.
Smaller forces face being merged into larger ones
Six chief constables, police authority chairmen and officials have released details of the agreed schemes.
One option is a "super force" for Beds, Cambs, Essex, Herts, Norfolk and Suffolk while others split the region north to south or east to west.
A preferred option must be submitted to the Home Office by 23 December.
One geographical option puts Cambridgeshire, Norfolk and Suffolk together in the north against Bedfordshire, Essex and Hertfordshire in the south.
The alternative is Bedfordshire, Cambridgeshire and Hertfordshire in the west with Norfolk, Suffolk and Essex in the east.
The need to consider amalgamation has come from a report by the Inspector of Constabulary Denis O'Connor, the former chief constable in Surrey.
His view is that forces of more than 4,000 officers were most efficient and his report called for mergers of smaller constabularies.
Police chiefs in the east have responded by meeting and agreeing to consider the three options they have announced.
Suffolk's chief constable Alastair McWhirter said: "We are having to work to a tight timescale if we are to submit a preferred option to the Home Office by 23 December.
"Our key objective is to find a consensus rather than expend a lot of energy with each force exploring multiple options for the future."
One critic of the whole idea is Suffolk coastal MP John Gummer who said: "There is no reason to change the system. We are a big county and I will continue the fight for a single Suffolk force."
Other politicians have also expressed concerns about the mergers but chiefs in most of the smaller forces have resigned themselves to some kind of merger.