Nick Clegg will today jettison many of the Liberal Democrats' long-standing policy pledges in an attempt to convince voters they would make the deep spending cuts needed to fill the hole in the public finances.
In an interview with The Independent, Mr Clegg revealed that many of the promises cherished by his party will be downgraded from official policy to "aspirations" since there would be no money to fund them. They are expected to include flagship pledges to scrap university tuition fees, provide free personal care for the elderly, and bring in a higher basic state pension.
The Liberal Democrat leader will ask his party's conference in September to make firm commitments in just three areas at the general election: a boost for education, the creation of "green jobs", and constitutional reform. These themes will be set out today in a mini-manifesto, A Fresh Start for Britain, which could run into criticism at the Bournemouth conference from activists opposed to such a slimline programme.
Mr Clegg issued a wake-up call to a party which has traditionally had a long shopping list of policies but been less convincing about how it would pay for them. Such an approach was fine for "an era of plenty", he argued, but would no longer carry conviction in times of "austerity".
He announced two rules that will govern his party's policies: no spending commitments without cuts elsewhere to fund them, and, similarly, no promises of tax cuts without increases in other taxes.
Mr Clegg wants to kickstart a debate that he claims Labour and the Tories are denying the voters as they squabble over headline departmental budgets in a Whitehall-speak that leaves ordinary people cold. The first task, he insisted, was to set out the values which inform spending priorities.
"The circumstances are utterly different from anything in the last 15 years. Our shopping list of commitments will be far, far, far, far, far shorter," he said. "We will have to ask ourselves some immensely difficult questions about what we as a party can afford. A lot of cherished Lib Dem policies will have to go on the back burner. They will remain our aspirations. They will remain our policies. But we are not going to kid the British people into thinking we could deliver the full list of commitments we have put to them at the last three or four elections."
Asked if that meant watering down pledges on tuition fees, personal care and pensions, Mr Clegg replied: "Some of these might be retained as policies that we could not honestly place at the forefront of our manifesto because we could not honestly claim they could be delivered in the first few years of the next parliament.
"I hope people will understand these are aspirations we will maintain but that, in these completely different circumstances, you can't carry on promising the same menu of goodies. It is just not plausible."
The Liberal Democrat leader insisted he had not drawn up a hit list of policies to be dropped. "The blunt truth is that everything is vulnerable. All the aspirations remain. We are setting out the criteria by which the Lib Dems will pick and choose from that menu."
Could the NHS, protected by both Labour and the Tories, face cuts? In theory, yes, because no area would be immune. In practice, Mr Clegg admitted, he found it "almost impossible" to think his party would not maintain health spending.
Cutting pledges for pensioners could be a risky electoral strategy, since older people vote in greater numbers than other age groups. But he floated the idea of an "inter-generational deal" under which people agree to bring down the public deficit so that tomorrow's generation is not saddled with crippling debts. His party's "unique selling point" will be education. So his plans to bring in a "pupil premium" to steer state support to children from disadvantaged backgrounds and to cut class sizes are sacrosanct.
Mr Clegg admitted that his approach will require "discipline" from his party, but insisted that he was "not looking for a fight" at the September conference. He conceded that, if his broad approach is approved, then a lively debate and some squabbles would follow among his frontbenchers as they fought to maintain pledges in their areas.
Is he using the crisis in the public finances to change the image of a party which has sometimes behaved as if money grows on trees? He denied that such a correction is needed. "All parties need to fight the election in a very different set of financial circumstances. We have operated in a period of largesse, when it has been very easy to appear to be generous. We now have a huge structural deficit akin to having fought a major war. If we don't sort it, we risk further economic meltdown."
Some will suspect that his tough new line is driven by a desire not to be outflanked by the Tories, who have been more open about the need for spending cuts than Gordon Brown. Mr Clegg insisted he had not even thought about the point. He accused David Cameron of "economic illiteracy" by demanding cuts during the recession, and Mr Brown of being "in denial" about the need for them afterwards. "The choices politicians make must be based on values – not an arbitrary, axe-wielding approach to public spending or a dismal exchange between Gordon Brown and David Cameron about percentages that sounds like an argument between different book-keepers."
Mr Clegg has grown in stature in recent months, winning over doubters in his own party with high-profile and timely interventions on the Gurkhas, the former Commons Speaker Michael Martin, the Trident nuclear missile system, and Afghanistan. Now his call for "candour" and a "grown-up" approach to public spending will test whether his party is prepared to grow up too.
* Education £2.5bn "pupil premium" for a million children from disadvantaged backgrounds, smaller classes and extra tuition.
* Tax Raise personal allowance to £10,000, reducing bills for most earners by £705 a year, funded by £17bn package of tax increases including abolition of top-rate tax relief for pension contributions and closing tax loopholes.
* "Green jobs" Package to create zero-carbon homes, insulate existing homes, schools and hospitals, and expand rail network.
* Political reform To clean up politics after MPs' expenses scandal, including proportional representation for Commons, elected House of Lords and state funding for parties.
* Universities Free tuition for first undergraduate degrees for full and part-time students.
* Care Free personal care for those over 65 at cost of £2bn.
* Pensions Higher "citizen's pension" with immediate restoration of link between state pension and earnings.
* Disabled £200 a year winter fuel payment.
* Post offices £2bn pledge to keep open rural post offices.