Leading article: The difficulty of riding two horses at the same time

As a former head of communications in the corporate world, David Cameron is well practised in the finer points of presentation and timing. His unexpected attack on the Government's approach to Islamic extremism earlier this week, and the release yesterday of a mini-manifesto - in fact a beefed-up version of a document sent out for party discussion a few months ago - were calculated to put the Conservatives squarely back on the political map.

The early summer saw the emergence of the first sustained criticism of Mr Cameron's leadership, essentially for what was perceived as lack of policy substance and drift. This was followed by justified concerns over a foreign policy vacuum during the recent Middle East crisis. Mr Cameron was right in sensing that he had to nip early discontent in the bud. The timing of this week's interventions was canny. With the Prime Minister on holiday and the Home Secretary taking a high profile on the threat from terrorism, the Conservative leader needed to say something that would show that he was on top of events. He succeeded, but only up to a point.

In taking the Government to task for not doing enough to tackle Islamic extremism, he effectively shattered the cross-party consensus on the issue, which had endured since the London bombings of July 2005. No wonder ministers seemed taken aback. In political terms, this was in every sense a smart move. It undercut John Reid's efforts to be seen as the toughest in the land, while telling the Tory shires what they wanted to hear.

Risking the perils of trying to ride two horses at once, Mr Cameron took issue with Mr Reid for freezing the Home Office budget at a time when the interests of national security might be thought to demand higher spending. But he also maintained his opposition to further restrictions on civil liberties in the form of 90-day detention without charge and the introduction of ID cards. There should, he said, be a "more hard-nosed defence of liberty". It remains to be seen how comfortably Mr Cameron will be able to balance this combination of authoritarianism and libertarianism.

The revised edition of the party's modernising mission statement contains similar potential contradictions. While there is much to welcome - the continued emphasis on green issues and tackling global poverty; proposals for decentralising responsibility in the NHS and the police; the pledge to introduce more streaming and setting in schools, as well provide for a "huge increase" in drug rehabilitation for young offenders - there is much else that is still ill-defined or could have the effect of contradicting these sensible objectives.

The key to the success or failure of Mr Cameron's project will be his ability to reconcile all these apparent contradictions. How can he square his opposition to Europe with his desire to force through radical environmental policies? How can he oppose state intervention while improving individuals' work/life balances? Much will depend on his policy reviews. He was undoubtedly wise to set aside time for the formulation of new policies, but 18 months is a long time for any party to be without thought-through ideas - particularly one wedded to the mantra of change.

Mr Cameron's frequent resort to generalisations and abstractions on the Today programme was another sign that all might not be well. This hesitant interview was among the least convincing he has given since he became party leader; his trimming of William Hague's statements on Israel did not enhance his authority. For almost the first time, Mr Cameron afforded glimpses of potential weaknesses. The time between now and when his policy groups report will not be plain sailing. The honeymoon is over; the real world awaits.