Leading article: Electioneering is the real agenda

Scarcely had the cheers for the Shadow Chancellor and his proposed tax cuts subsided in Blackpool than the Prime Minister flew into Iraq to announce that 1,000 British troops would be home in time for Christmas. The number might be smaller than many had hoped. But this announcement, along with Gordon Brown's high-profile meetings with Iraqi leaders, the US military commander and British troops, made for an eye-catching day's work.

At a stroke, the Prime Minister and plans to reduce Britain's troop presence in Iraq had replaced the reinvigorated Conservatives in the headlines. If there had been any doubt before then, there is none now: the leaders of both parties are playing for the highest stakes here – victory in the event of a snap election.

This does not mean that the decision has been taken. What it does mean is that the Prime Minister is doing absolutely nothing that would halt speculation; he is keeping his options glaringly open. His Iraq trip can be seen as necessary preparation for his expected presentation to the Commons next week. It can also be seen as politics in the ruthless raw.

Already the broad outlines of the campaign – if there is to be one – are apparent. For Mr Brown, the running theme is seriousness, responsibility and business as usual. But he still needs to provide answers to some outstanding questions: whether, and how, he intends to conclude Britain's worst foreign policy mistake since the Suez calamity is one. Another will concern the specifics of his "personalised" public services.

The Conservatives' undertaking, sprung on a delighted conference by George Osborne, to slash inheritance tax and stamp duty, while soliciting a contribution from non-domiciled foreign residents, throws down an unheralded gauntlet to Labour. Mr Brown and his Chancellor can choose whether to meet the challenge by discrediting the Tories' calculations, or the principle of cutting taxes for the better off. This crescendo of calls issuing from Blackpool for a referendum on the EU treaty has also shown the Tories in a traditional, populist mode that Mr Brown and his Foreign Secretary need to do more to counter. That Tony Blair granted the principle of a referendum on the earlier version of the treaty does not make their task any easier.

As Conservatives opened their conference on Sunday, the speech that David Cameron delivers today was billed a make-or-break speech for his leadership and his party. After a better week than the Tory organisers expected, Mr Cameron's speech will still be make-or-break, but no longer for Mr Cameron's leadership. The speech, and its reception, will be what clinches the Prime Minister's decision to call – or not to call – an election.