John Reid has admitted his head is "on the block" over the future of the Home Office and acknowledged he faces the sack if he fails.
The Home Secretary, who described his task in turning round his beleaguered department as the toughest he has faced, will set out plans next month to rescue the Home Office.
He has criticised parts of the department as "not fit for purpose" after a succession of controversies including the release of foreign prisoners and the row over "lenient" sentences.
He and Sir David Normington, the Home Office Permanent Secretary, addressed 200 managers yesterday in a move to win support for sweeping reforms.
Afterwards, Mr Reid said: "We together will be putting our head on the block."
The Home Secretary said his new job was "the biggest challenge I have ever faced, is the biggest risk and is even more risky since I decided to be public about the extent of the problem and the extent of the challenges".
Asked what would happen if he failed to overhaul the department, he told reporters: "What happens when any cabinet minister fails at the Home Office? You guys are more aware than I am. I think we've lost four."
Mr Reid has in fact had three predecessors under this Government - Jack Straw, David Blunkett and Charles Clarke. He stressed later that he was not dismissing them as failures.
Mr Reid, who said he wanted to stay in his post until "the job is seen through", said the arbiters of his success would be the media and the public. The yardsticks of his performance would be the visibility and responsiveness of the police, building a "fair and effective system of managed migration" and ensuring the courts were not "skewed towards" protecting offenders.
He disclosed that a task force of 25 - drawn from "the brightest and best" in the Home Office - is working on next month's plans.
Mr Reid and Sir David said they had no plans to split up the Home Office but Sir David hinted that failing parts of the department could be turned into agencies at arm's length to give managers more freedom to take tough decisions.
Extra senior staff are likely to be hired in the Immigration and Nationality Directorate by Mr Reid, who is appealing to Gordon Brown, the Chancellor, for emergency cash for the reform to be implemented.
Mr Reid toned down previous remarks about the possibility of sacking civil servants involved in the foreign prisoners fiasco.
And Sir David indicated that there may be other disciplinary options rather than sackings. He said: "There are conversations going on but I don't really want to talk about how I'm dealing with individuals in the Home Office."
Mr Reid faced embarrassment yesterday when his suggestion that parents should know more about where paedophiles live was condemned by the Children's Commissioner. A statement from the commissioner's officials said introducing a "Megan's law" in the UK could put more children at risk by forcing paedophiles underground and encouraging vigilantism.
In the Commons, David Cameron attacked Tony Blair for taking his "eye off the ball" over problems in the criminal justice system. The Tory leader said that after nine years in power and countless initiatives, Mr Blair had no one but himself to blame for the Home Office failings. "You are out of touch and you cannot be the right person to sort it out," he said.
Mr Blair retorted that whenever the Government proposed tougher measures, the Opposition voted against. He said changes planned by ministers would act as a test for the Tories.Reuse content