With a faux dramatic flourish, the cover will be torn off to reveal the latest propaganda effort for the cameras to beam into voters' homes. This has become one of the most hackneyed stunts of election campaigning. And also among the most bogus. Sometimes, the unveiling will be the only occasion that the poster actually appears anywhere. The point of the exercise is to get political advertising on to the telly for free.
Can I make a suggestion to the broadcasters? Stop televising these fake 'events' which exist only for the purpose of being televised.
Labour did not even have to go to the bother of staging an unveiling to provoke a controversy about the advert which stuck the heads of Michael Howard and Oliver Letwin on flying pigs and a second poster which appeared to depict the Tory leader as a Fagin-like character. Labour's campaigners have not really been embarrassed by the accusations that these posters were anti-semitic. One of the Prime Minister's propagandists chuckled to me that they had got a double hit out of them by generating additional free publicity for the posters that have appeared as replacements on the party's website.
There are four of them. Each is about the government's record: the last Tory government's record. Each features the leader: the Conservative leader. It is universally believed among Labour's campaigners that the more the voters see of the Tory leader, the less they like him. That is why, in the words of one of them, they are 'playing hard on Howard'.
The character of the opposing leader is fair game. I will be amazed if the Tories do not unleash a sustained assault on Tony Blair as a man who cannot be trusted. It is equally legitimate for Labour to attack the record of the Tory government of which Michael Howard was a prominent member. For many years after the winter of discontent, the Tories went on using it to bash Labour. I am neither surprised nor shocked that both parties are seeking to exploit the freedom of information legislation to dig up stuff to hurl at each other. Politics, especially at election times, is not for wusses.
What is disappointing is the puerile and unoriginal quality of the propaganda. Flying pigs? Oh dear. Can the inventive minds of Labour do no better than that?
Politicians may govern in prose, but the best of them campaign in poetry. Tony Blair's phrase-makers have just unveiled their campaign slogan. 'Forward, Not Back'. Yup, that's it. I suppose it has the merit of being brief. But poetry it ain't. It is as uplifting as 'Open Other End', 'This Way Up' and 'Now Wash Your Hands'.
Though it speaks of going forward, this is a retro slogan, an echo of Tony Blair circa 1997. One minister closely involved with the Labour campaign even explained the thinking behind it by telling me: 'We are going back to New Labour.' Alastair Campbell has returned. Actually, he's been working on the Labour campaign since before Christmas, but so everyone would be in no doubt, the sultan of spin just couldn't resist being snapped striding up Downing Street.
Returning, too, is the original Blairite device of defining the political contest as one between old, backward Tories and new, dynamic Labour. The Conservatives will ridicule Mr Blair for trying to sell himself as the future when he has now been in Number 10 for longer than Harold Wilson. But it is also a com mentary on the state of the Tories that Labour can campaign like this.
Both parties originally planned to fight this election in new ways. Both are already falling back into old habits. The Tories were supposed to have learnt the errors of William Hague's catastrophic 2001 campaign. The consensus among Conservatives after that landslide defeat was that they were massacred because they had failed to understand and engage with the voters' concerns about public services.
They would not make the same mistake again, so the Tories told themselves. It is true they have moved on in some respects. They go into this election saying that they can match Labour spending on hospitals and schools. But it is not health and education that the Tories have chosen to big up. They have returned to those favourites of Mr Hague last time around: to crime, to immigration and, more modestly, to tax cuts. It is to those subjects that the Tories have devoted most energy and attention since the new year.
This lapse into their default mode speaks volumes about Conservative prospects and the gloomy view they take of them. Never mind the polls. Forget the odds at the bookies. Observe what the Tories are themselves doing. They are not attempting to challenge Labour in areas where the government is ahead, which would be the way to fight with a view to winning the election. The Tories are concentrating their campaigning on subjects where majority opinion already tends to favour them rather than battling to become more competitive in territory where they are behind. It is a strategy for rousing the Tory core vote rather than reaching out to woo the centre ground.
If the Conservatives are still fighting the last war, then Labour is doing much the same. This makes slightly more sense for Tony Blair; at least he won the last war. But this is not what he and his campaigners originally planned to do. At the time of the party conference last autumn, I had many conversations with his strategists. All were agreed. They could not expect to win in the same fashion as they had in 1997 and 2001. The repertoire would have to change. It would not be enough to brag of the government's successes and slag off the Conservatives as slashers and burners.
Gordon Brown was given another grievance to nurse when it was suggested by the Blairistas that running on the strength of the economy was not the route to another handsome victory. No, the way to win was to present a vibrant, even contentious prospectus for a third term. The 'forward offer' - ugh phrase - was what the election had to be about if Labour was to galvanise enough support at the polling stations to secure its third term in a convincing fashion.
What happened to all that? The one positive Labour has been pushing is the economy, though it doesn't seem to have made Mr Brown any happier his antagonists in Downing Street have decided it is worth boasting about after all.
The Labour campaign has so far been characterised by negative attacks on Michael Howard and 'Tory cuts' and defensive tactics designed to blunt the saliency of issues where the government feels vulnerable. The Conservatives promote a change in the law on the degree of violence a householder can mete out to intruders, so the government produces a new good-housekeeping guide about how to bash a burglar.
The Tories go large on immigration; this week, Labour will make its own noise on the subject. The Conservatives make an issue of school discipline; so does Labour. The Prime Minister's allies are quite frank about it: 'The strategy is to try to close down weak areas before moving on to the more positive areas.'
The move into those more positive areas is planned to begin at the end of this week when Tony Blair makes his speech to the party's spring conference. It can't come too soon. There is no point whingeing about negative campaigning. They do it because it works. But the returns will be rapidly diminishing.
The techniques being deployed so far may be tried and tested, but three more months of this will leave many voters tired and politicians even more untrusted.