Johnnie Walker, the Diageo whisky brand, is reviewing its global advertising account.
Bartle Bogle Hegarty has held the business since 1999 and said it would "vigorously defend" the account.
BBH created the "keep walking" slogan that has run in more than 100 markets since 2000.
Diageo is handling the process and has issued an RFI for a shortlist of agencies, including BBH, to participate.
Guy Escolme, the global brand director at Johnnie Walker, said: "The brand’s relationship with BBH has been hugely successful, with the agency producing award-winning work of outstanding creativity.
"As the market leader, Johnnie Walker feels the time is right to invite selected agencies to look at how we take the brand into the future."
The brand also works with agencies including Anomaly New York.
This article originally appeared on campaignlive.co.uk.