Tony Blair embarks on the most difficult phase of his leadership next week as he introduces the next stage of a controversial legislative programme without the man seen as crucial to his re-election hopes at his side. A tough approach to security in the face of terrorism and no-nonsense law and order policies to counter rising public fears about violent crime were a product of David Blunkett's tenure as home secretary and lay at the heart of Mr Blair's strategy for winning a third term in office. Mr Blunkett's sudden departure leaves the prime minister politically weakened, dangerously exposed to a possible leadership challenge and facing the prospect of defeat in an anticipated May general election. Mr Blair has turned to 54-year-old Charles Clarke, the former education secretary, to take on the heaviest workload in British politics after a messy affair, a public child-custody battle and, ultimately, a complex visa scandal led to Mr Blunkett's resignation. Mr Clarke has been dropped in at the deep end. On Monday, he presents to the Commons the plans drafted by Mr Blunkett for compulsory identity cards. Civil rights concerns over ID cards have deeply divided the cabinet in recent months and Mr Clarke is understood to have had private reservations about their introduction in the past. A renowned political bruiser and one-time Marxist, Mr Clarke is close to the prime minister but few believe he has the personal appeal or the ability to set his beliefs aside to sell draconian security policies to sceptical, liberal-minded voters. It took Mr Blunkett's unique blend of left-wing credentials and right-wing zeal to translate measures that play fast and loose with civil liberties into law. He was seen as the best home secretary the opposition Conservative Party never had and his style suited Mr Blair's conservative approach. During Mr Blunkett's watch, police standards were raised, an uncompromising crackdown on bogus asylum seekers was imposed and terrorist suspects were detained without trial. The latter was on Thursday deemed to be in contravention of European human rights legislation by Britain's Law Lords. Mr Clarke's education portfolio has been handed to Ruth Kelly, a 36-year-old Labour high-flier who has had a meteoric rise through the party ranks. Her old job as cabinet office minister, in turn, has gone to David Miliband. All three new cabinet appointments are staunch Blairites brought in to see off any leadership challenge from the ambitious chancellor, Gordon Brown.