Tom Dery, the agency's Asia-Pacific and US executive chairman, said: "Kim has got a three-year contract and we've had some initial discussions, but no decision has been made."
Industry sources claim the agency has been making approaches with a view to filling Walker's shoes.
The news comes after it reported a revenue drop of almost 6 per cent, year on year for the first half of 2007. Singapore, Thailand and Shanghai each posted losses during the relevant period.
Walker said: "Some of the individual countries are not performing the way they should, but action has been taken."