Members wanting to vote now have until noon next Friday, after the deadline was extended because of the effects of the postal strike.
NHS Lothian director of communications Jenifer Stirton and communications director at the Department for International Development Paul Mylrea are in the running for the post.
The role of treasurer will also be elected, with Lisa Shaddick MD of DA Public Relations and Sally Sykes, comms director for the Health and Safety Executive, vying for the position.
Candidates' statements can be viewed here.
