But a DfT spokesman said this afternoon: 'We are not making a decision today, but will do so by December 9.'
Seven people - six passengers and a passer-by - were killed when a London to King's Lynn train derailed close to Potters Bar station in Hertfordshire in May 2002 after passing over a defective set of points.
In October this year, the Crown Prosecution Service ruled that no criminal charges would be brought in relation to the crash.
The ruling meant there would be no possibility of staff from Railtrack, now Network Rail, and from Jarvis, the company responsible for maintenance on the stretch of track at Potters Bar, facing manslaughter charges.
However, the CPS said the case would now be referred to the Health and Safety Executive to consider whether or not proceedings under the Health and Safety at Work Act were appropriate.
Campaigning lawyer Louise Christian said Mr Darling would be making a decision today.
The Department for Transport said: 'We have always said that we would consider the case for a public inquiry after the CPS decision on manslaughter charges and we are now doing so.'
Ms Christian represents the Taiwan-based parents of Chi Hsin Lin who died in the crash.
Ms Christian said the Lins had brought judicial review proceedings in the High Court challenging the failure of the Secretary of State to have a public inquiry.
An HSE report into the Potters Bar crash said poor maintenance led to the points failure which caused the derailment. Nuts were loose on the points, which meant the West Anglia Great Northern line train came off the tracks.
Ten days after the crash, Jarvis said sabotage could not be ruled out. But the HSE said it had found no evidence of sabotage or deliberate unauthorised interference with the points.
Ms Christian said today: 'The bereaved families have been asking the Secretary of State for a public inquiry since the crash happened. As is well known, Jarvis claimed at the time that the crash was due to sabotage, not to negligence.
'It took over two years for Network Rail and Jarvis to admit liability. Unless there is accountability and an acceptance of responsibility the public cannot be sure that it will not happen again. Only a public inquiry can get to the bottom of what happened and ensure full accountability. An inquest will not do this.'