The consultation exercise over plans to expand the congestion charge zone across west London ends on Friday.
The process cost £1m and could lead to the £5 road toll being extended to cover more of Westminster and most of Kensington and Chelsea.
Some residents claim they did not receive information about the proposals and have begun an email petition.
The scheme began in February 2003 and charges drivers within an eight-square-mile zone of central London.
The extended boundary would stop just short of Shepherd's Bush to the west, run as far north as Kensal Green Cemetery and down to Chelsea Embankment in the south.
It could be in place as early as 2006.
But any expansion would only take place after Transport for London has assessed two years of the current scheme's performance and if Mr Livingstone wins this year's mayoral elections on 10 June.
The expansion would cover a much bigger residential area; about 230,000 residents compared to the 150,000 people living in the current area.