By Nick Assinder
Political Correspondent, BBC News website
Home Secretary Charles Clarke probably knows an admission of guilt and an expression of regret will not be enough to calm the furore sparked by the revelation that 1,000 foreign prisoners have been freed and escaped deportation.
Similarly, while the prime minister is currently expressing his full confidence in his home secretary and junior minister, Tony McNulty, he will also know that there will now be intense pressure for a full explanation of exactly why the mistake happened.
At the very least it seems virtually certain that Mr Clarke will be forced to come before MPs to make a full Commons statement on the affair amid anger he attempted to deal with it through a written statement.
The opposition parties have so far held back from demanding any resignations, although Mr Clarke clearly expects such calls to come and has insisted he is staying put.
Former Home Secretary David Blunkett, who ran the department while some of the prisoner releases were taking place, supported Mr Clarke but said heads should roll over the affair - presumably amongst officials.
But the Tory and Liberal Democrat frontbenches, along with MPs from all sides, have already expressed their horror at the blunder and Conservative spokesman David Davis has claimed the "serial incompetence" had placed the public at risk.
Downing Street, meanwhile, has claimed there was no policy failure - suggesting ministers knew nothing off the affair, which was down to officials.
The prime minister's official spokesman said the problem was the result of a "breakdown in communications," adding it was "unreasonable to expect ministers to know what is going on in every nook and cranny in their department."
However, he also admitted that the prime minister was not pleased by the affair.
And MPs were already suggesting the blunder was far from part of the "nooks and crannies" of the department and, even if ministers did not know what was going on, their job was to take responsibility.
Mr Davis has demanded explanations
Some were already saying it would be unacceptable if officials were the only individuals to take the rap.
Inevitably, questions were also being asked about exactly when ministers did first know about the mistakes and why they are refusing to name those who have been freed into the community.
More widely, the affair plays directly into fears over Britain's immigration and prisons systems, both of which have been claimed to be struggling to cope with their workloads.
And the timing of this revelation could not be worse, coming just over a week before crucial local elections where the issues of immigration, asylum seekers and law and order are again expected to play a leading part.
For now, opposition parties are satisfied with demanding a full Commons explanation from Mr Clarke.
It is only when they get such an explanation that they will decide whether this is an affair that warrants demands for resignations.
It is certain to be a hugely uncomfortable few days for the Home Secretary and, inevitably, the government as a whole.
And Tony Blair certainly does not need another distraction of this sort from his attempts to get on with the job of reforming the public services and securing his legacy.