And so the election descends to the playground. Having lost on tax and spending, scored an own goal on immigration and failed to win over business, the Tories' last gasp is a "liar, liar, pants on fire" attack on Tony Blair. By turning the vote into a referendum on the question "Do you trust Blair to tell the truth?", both of the main opposition parties hope to prevent the landslide that threatens to bury them once more.
On the face of it, putting trust and truth front and centre looks a smart ploy. Blair does indeed poll badly on questions of trust. And surely, the British people want a man of his word in No 10? Some polls have shown a majority believing that the Prime Minister consistently lied over Iraq.
At the start of the campaign, ministers were admitting that trust was a big issue. Jack Straw - the invisible man of the election - said voters would have to decide which party "best deserves" their "future trust". And Gordon Brown's high trust levels were one reason for the re-emergence of the dual monarchy with Blair.
Yet Straw was wrong. We do not elect our MPs, political parties or even leaders on the basis of a straightforward assessment of their honesty or trustworthiness. If we did, Margaret Thatcher would not have won a single election. In each of her contests, she was less trusted as an individual than her opponents, but more trusted to get on with the job. As Kieron O'Hara, senior research fellow at the University of Southampton and author of a book on trust, wrote in the NS on 8 September 2003, people trusted Michael Foot as a man who would stick to his principles - "it was just that they didn't want those principles applied in Britain".
Similarly, while Blair is not widely trusted to tell the truth, this does not weaken him against his opponents. Pointing out that the PM is not trusted is not very different from pointing out that he is a politician. Three-quarters of the adult population do not trust politicians as a group "to tell the truth". Roughly 87 per cent say politicians do not keep the promises they make before elections, and 92 per cent reckon they never give "a straight answer".
This helps to explain why Blair, despite being widely considered a bit of a fibber, is heading for a third substantial victory. Seventeen per cent of respondents to a poll for Sky News said they had trusted the PM, but lost that trust after the controversy over weapons of mass destruction in Iraq. But another 39 per cent had never trusted him anyway. Politicians in general, and Blair in particular, worry about loss of trust without seeming to notice that they never had much of it in the first place.
Even if Blair's ability to draw out votes has been reduced by the erosion of his trust ratings, this may not have the impact many fear. The chattering class may talk about a new "presidentialism" in politics, but people still vote on other bases. These, according to MORI, include a party's policies on national issues; the impact of its policies on the local area; the values it stands for; and the quality of the local candidate. All these outrank the party leader as an influence on voting intention. In practice, the leader carries a good deal of responsibility for communicating policies and values. Yet the election is not a joust between Blair and Michael Howard.
Opinions on trust in individuals are in any case very difficult to collect and interpret. Trust is not a simple, binary issue. As Onora O'Neill said in her 2002 Reith Lectures, it is "multifaceted". In other words, we trust certain people to do certain things. Trusting someone to turn up on time is not the same as trusting them to babysit your child, which in turn is different from trusting them to get you the very best mortgage deal. Similarly, when voters are asked which leader they "trust to deal with" a certain issue, the PM outperforms Howard on education and health, tax, terrorism, the economy, Europe and representing Britain abroad. They are level-pegging on crime. The only issue on which Howard is trusted more than Blair is immigration.
For a party leader, the perception of capability is crucial. This is why leaders who are widely seen as more honest than others - such as Charles Kennedy - do not necessarily convert their veracity into votes. Throughout history and across the world, politicians seen as less than entirely frank have won office: think Richard Nixon, Bill Clinton and Silvio Berlusconi.
Given the choice between candour and capability, voters go for capability every time. If anything, voters seem to prefer their leaders a tad dishonest. Perhaps they are more sophisticated than commentators recognise, seeing that success in politics often requires an ability to present arguments artfully rather than straightforwardly. All successful politicians have a ruthless streak in them, which they generally try to hide from the population. But voters can tell which politician is willing to knife his or her best friend in the back if necessary, and who would be a reluctant executioner. It is the former who tends to get the votes. Politicians spend a great deal of time trying to appear as "reasonable" folk, but the evidence is that, although we want reasonable people as our friends and neighbours, we want some steel in Downing Street.
In any case, if Blair is economical with la verite, that is not exactly breaking news. Most of those for whom this is a decisive argument to desert Labour probably reached their conclusion months, if not years, ago. The loss of trust in Blair has already been priced into the political market. Despite a fairly settled view that he is not above the odd porky, the chances of him having to ring the removers on 6 May have been all but scuppered. Who wants a plaster saint for PM? Not the voters, by the looks of it.