The Huntsworth-owned agency's CEO Mike Morgan told PRWeek: "We're very proud of our work for EDF Energy over recent years and wish the business all the best for the future."
Several agencies were contacted last month about the brief, with the successful agency expected to be announced in March next year.
The brief, believed to be worth around £300,000 per year, is to support EDF's brand and marketing activities, as well as creating brand and consumer PR campaigns.
Current work includes campaigns around EDF's #prettycurious programme, which aims to help girls consider careers in science, technology, engineering and maths (see video below).
Earlier this year the French-owned energy giant, which supplies electricity and gas to around five million British homes and businesses, awarded Portland a new combined public affairs and corporate comms brief, beating Edelman, as well as incumbents Brunswick and MHP.
A spokeswoman for EDF Energy said: "The consumer PR tender has no impact on the relationship we have with Portland, as they are working to separate briefs."
Elsewhere in the energy world, PRWeek reported last week that Golin is looking to retain its consumer and corporate brief with npower, which is being reviewed.