Promising change is a risky tactic. Just look at Barack Obama - or, indeed, Gordon Brown.
But, unfortunately, leaders of the opposition have no choice: achieving change is why you are there, so that is what you talk about.
Winning an election is the easy part.
Really changing the country is much harder. And, in an age that demands instant gratification, it also suffers from the severe disadvantage of taking absolutely ages.
Forget about mending broken Britain, creating a culture of entrepreneurship, or any of the big changes David Cameron has promised.
There are some more immediate roadblocks in his way. First, the media. How can this be when most newspapers are backing the Tories? But that omits the pervasive influence of the BBC. This is not a crude political point.
The BBC appears to see its job as being to treat all politicians as - to quote Jeremy Paxman - 'lying bastards'. But Tory 'bastards' are held to be the worst sort by a corporation whose inherent anti-free market inclinations are a reflection of its constitution and ethos.
Then there are the unions. Apparently they have a war chest of £25m to fund public sector strikes. We must pass over the irony of action that will hurt the poor, sick and unemployed more than it will inconvenience suburban Tory voters.
In any case, although there will be some immediate pain, Cameron will relish the opportunity to test himself against the likes of RMT general secretary Bob Crow or PCS general secretary Mark Serwotka.
Next,there is the senior civil service.
This is a lot trickier.
The Tories have dark suspicions that the mandarins have been politicised.
That might be true in a few instances, but it is certainly not generally the case.
Civil servants are not anti-Conservative: they retain their lordly contempt for all politicians. What has happened - and I speak from personal experience of a previous regime change in 1997 - is that after a longish period of one-party rule, departments become habituated to the outlook and approach of their ministers.
It takes time to turn that around - and time is not a commodity that the new Conservative Government will have.
This will be worse for the Tories than it was for Labour.
The civil service and New Labour share a conviction that big government is better: the man in Whitehall really does know best.
This is a natural part of the professional self-esteem that motivates any bureaucracy.
The civil service will do its best for Cameron, but it will be a struggle.
Then there is the broader public sector.
This is not just a question of a few permanent secretaries. There was a good reason why Tony Blair spoke of 'the scars on my back' when talking about achieving public sector reform. All prime ministers have that hopeless feeling of pulling the levers in 10 Downing Street - and nothing happens. It's why they all end up playing at international statesman instead: so much easier to solve others' problems.
Finally, there is the enemy within: Cameron's own party.
Gone are the days when the party had a sound ballast of chaps who had made a bit of money, served as an MP out of duty and trooped obediently through the lobbies. The Tories used to be the stupid party: now it seems to be full of 'action men and women' who are also, by and large, a lot less centrist than their leader.
Some will be bribed with office, some will be bullied by the whips, but others will continue to have ideas.
And, as any PM will confirm, backbenchers with ideas have a nasty habit of turning into rivals if things get rocky.
Relations between the leader, his key advisers and the shadow cabinet are already said to be difficult without the backbenchers.
Good luck, Dave.
VIEWS IN BRIEF
- Who are your five fantasy dinner guests from the political world?
Cato the Younger - heroic tales of resisting tyranny; Richard Neville, Earl of Warwick - advice on political manipulation; Charles James Fox, raconteur and sybarite; Calvin Coolidge, 30th US president - laconic wit; Percy Bysshe Shelley - not really a politician, but a revolutionary wild card and good talker.
- Predict one thing that will happen in the week running up to the election.
There will be a Tory wobble but we will all have died of boredom by then.
- A hung parliament: good or bad news for public affairs?
Political destabilisation is good for agency incomes, but bad for research teams.