New rail performance figures showing that more trains have arrived late since Railtrack was put into administration are to be published this month, putting Stephen Byers's hold on to office under fresh threat.
The Transport Secretary has warned that the figures will be "grim" and they are certain to reopen the Tory attack on Mr Byers for forcing Railtrack into administration.
The figures to be issued on 18 March show that punctuality plummeted between October, when he put Railtrack under administration, and December.
Mr Byers was warned by his press chief Martin Sixsmith not to let his special adviser Jo Moore "bury" the figures on the same day as Princess Margaret's funeral, which sparked the resignation row.
However, Mr Byers intends to come out fighting over improvements in train performance that have been delivered since the figures were collected for last year by the Strategic Rail Authority.
"The Tories have been claiming that delays were 40 per cent but it's not that bad," said a Whitehall source. "They are grim but they usually are in the autumn."
Mr Byers is ready to blame Railtrack bosses for part of the decline in performance, accusing rail chiefs of focusing more on winning compensation for their shareholders than running the railways.
Leaves on the line are also blamed for contributing to lateness of trains. The attempts to improve safety which has resulted in fewer signals passed at red since January have also led to more late trains. "Drivers are driving more slowly into stations, and it has a knock-on effect on punctuality," said the source.
Mr Byers has told colleagues that it would be wrong to compare the latest set of figures with the year before when the Hatfield crash led to chaos on the rails.
Rail industry insiders have confirmed to The Independent on Sunday that performance figures have dramatically improved since the end of last year, as the new management team which came in to replace Railtrack took over. Those figures will not be published for some months.
The latest SRA figures will be broken down for the first time according to train operating companies, enabling passengers to see whether their services have declined or improved. Most will find that there have been more delays.
The Transport Secretary is planning to use the renegotiation of contracts to run services over the next two years to reduce the number of train operating companies from around 25 operators to about five. That could answer one of the main calls for a more coherent approach to the network.