TBWA's appointment is expected to be confirmed by Friday after a final round of pitching and research last week. However, Transport for London denied a decision had been taken.
M&C Saatchi was controversially appointed to the congestion charge account in October, after TfL opted to combine the business with its corporate account. M&C Saatchi beat Leo Burnett, McCann-Erickson and the incumbent, Partners BDDH, to land the corporate business. However, rivals for the congestion charge account complained, forcing a reopening of the pitch.
TfL's general manager of marketing communications and corporate design, Charlie Edelman, was asked to delay her departure from the role in order to oversee the pitch.
Advertising is expected to play a crucial role in the launch of the scheme, which was green-lighted by Livingstone last month. Local Conservatives have campaigned against the proposals, which will use camera identification of number plates to charge motorists £5 a day for using roads in central London.