The communications team is looking to cut costs as part of the council's overall package of spending reductions, which amount to £9m by next March.
A consultation process is under way and a decision on the extent of the job cuts is expected to be made by September. The bulk of the redundancies are expected to come from Westminster's campaigns team.
Westminster director of comms Alex Aiken said: 'It is prudent to reduce now, given the inevitable trend in public spending. A smaller team can do more if it is focused clearly on tangible objectives.'
The redundancies will come as the comms department merges the digital and media relations teams and develops a 'more focused approach to campaigns'. The media relations team will now have responsibility for digital.
Earlier this month, in a column for PRWeek (prweek.com/uk, 7 July), Aiken wrote: 'PR leaders in public service now need to develop a three-year plan on how they can deliver high quality communications with at least a third less of the budget that they have today.'