Green founded Wakefield-based PR firm Green in 1993. The company ceased trading in July this year, but previously worked with clients including Asda and West Yorkshire Police.
His seven pledges for creating a better CIPR include strengthening professional standards, creating 'IdeasBanks' and extending campaigning on diversity issues.
MacKenzie is the managing dircetor of Liquid, a PR consultancy that operates across London, Birmingham, Jersey and Guernsey. He is also an executive board director for the CIPR.
MacKenzie pledges in his mission statement that, if elected, he will ensure CIPR qualifications and training resources promote best practice, make membership more valuable and deliver the most successful membership campaign to date.
Canvassing is now underway with online voting opening on 28 September and closing 12 October. Results will be announced on 16 October.
The winning candidate will serve a three-year term on the CIPR Board of Directors as president-elect in 2016, president in 2017 and past president in 2018.