Electoral politics has never been so volatile. Not only is this the most open election since the 1920s. The uncertainties are a symptom of deeper discontents. Even before the expenses scandal, the party system rested on a shallow foundation of public consent. Now, everything is far worse. The anti-politician mood is unreasonable and self-indulgent. But it has a firm grip on public opinion. That is unlikely to change in a mere two and a half weeks.
It is equally unreasonable that this should benefit the Liberals, but it will. For years, they have marketed themselves as the anti-politician party, and succeeded, which is absurd. In a pejorative sense of the word – Shakespeare's "vile politician" – they are the most political of all the parties. They will say almost anything to win votes. In the two major parties, most politicians at least started out with a set of beliefs. Talk to them, and you can understand why they came into politics and why they joined their party. Among Liberals, that is much more difficult.
But it is hard to convince the voters of this. The delusion that the Liberals are the only decent party is too deep-rooted. This means that whenever they are under attack, the Liberals can immediately retreat into sanctimoniousness. "Aren't these politicians awful," they say – and the public will fall for it. Chris Patten once said that trying to argue with Liberals was a hazardous business: a bit like insulting the vicar and then agreeing to wrestle with the greased pig at the village fête. Lord Patten might have been speaking from foreknowledge. He eventually lost his seat to the Liberals.
The Liberals seem to be able to get away with anything. During Thursday's debate, Nick Clegg announced that in the Ministry of Defence, there were 8,000 bureaucrats working on communications. As I listened, I thought: "Eh? That can't be right. We know this Government is disappearing up its own spin, but this is ridiculous." It was. The true figure is 178: still too high, but not lunatic. Mr Clegg was guilty of a 40-fold exaggeration, but that was not his worst offence. The 8,000 figure was utterly implausible. Anyone who could give it credence must have a wholly deficient sense of reality.
It will not be easy to convict him of this, but there is another way to nail the Liberals which might resonate with the public. Mr Clegg is proposing an amnesty for 600,000 illegal immigrants. The experience of other countries reinforces the obvious common-sense point: amnesties attract illegal migrants in the way that a lamp attracts moths. "We'll smuggle you into Britain," the people-traffickers will be saying. "Then you won't have to wait long for the next amnesty." As the Liberals rarely think through the consequences of their policies, they may not realise this. But in effect, they are calling for uncontrolled immigration.
On Thursday, David Cameron will have to cope with the problem that Chris Patten identified. Mr Cameron will have to be sharper than he was last week, without opening himself to the charge of bullying. He will have to hit the Liberals hard, with a smile on his face. It is not an easy task, but David Cameron is used to that.
Moreover, it is a much easier challenge than the one which some politicians are facing. David Cameron can raise his game. Nick Clegg can give another good performance. But Gordon Brown? He did everything Mandy told him. As well as some jabbing debating points, he made jokes. There was a touch of self-deprecation. Throughout, he tried to smile. But the debating points did not strike home, the jokes were too contrived, and the smile was more like a rictus: an anaemic midwinter sun glinting on a coffin plate. Nothing worked. The Prime Minister was at his absolute best, yet he came across as old and tired and stale and desperate. That is not going to change.
Even so, he deserves no sympathy. A few days ago, his party was guilty of the nastiest stunt in British political history. Anyone with cancer is under stress. Sometimes, gravity's normal ration of 14 pounds per square inch must feel more like 14 tons. It is easy to alarm cancer patients, and that prospect had people in Labour headquarters rubbing their hands with glee. A few days ago, around 200,000 cancer sufferers received literature from the Labour Party alleging that the Tories would deny cancer patients the treatment they need.
There is no truth in this. On the contrary: as part of their commitment to the NHS budget, the Tories would ensure cancer sufferers were given drugs which are currently unavailable on cost grounds. Those who try to exploit sickness in this way are sick themselves: suffering from a cancer of the moral sense. Gordon Brown has accused Goldman Sachs of moral bankruptcy: strong words, and not as undeserved as they ought to be. So what language would he use to describe the way in which his party has exploited people who are seriously ill? Next time you hear Mr Brown prating away about the values he learned in his Scottish manse, remember the cancer patients. Before he leaves office, this Prime Minister is determined to drain the cup of hypocrisy and dishonour.
His party may also have broken the law. Who acquired those patients' names and addresses? How was this done? There is a Data Protection Act, and the ill deserve its protection. There ought to be a thorough investigation, followed by prosecutions. If those responsible end up in prison, it might deter other evil-minded characters from emulating them.
For Gordon, things can only get worse. Although Peter Mandelson is putting on an admirably brave face, one would like to know what he really thinks. After all, he is responsible – for Gordon Brown's survival. Admittedly, the plotters were inept. As they did not hang together and strike together, they were struck down and hanged one by one. Some of them even ended up grovelling at the feet of bogus lobbyists. But Mandy's tireless, serpentine cunning – a flattering word here, a threat there – had its effect. He saved Gordon, and thus made it possible for Labour to come third in the popular vote: not the contribution that Lord Mandelson wanted to make. By ensuring that Mr Brown fought this election as PM, he may have helped Nick Clegg to fight the next one as Leader of the Opposition.