Election manifestos are contracts with voters. Under our parliamentary system, their promises are supposed to be broken only in exceptional and extreme circumstances.Boris Johnson's manifesto, his contract with us that he effectively signed in December 2019, said "I guarantee we will not raise the rate of income tax, VAT or National Insurance".Tomorrow - barring a full-scale cabinet revolt that forces a climbdown - he will break that guarantee, with a rise of 1.25% in the rates of national insurance paid by employees and employers to raise more than £10bn a year.So does the Covid-19 crisis, and its deleterious impact on the public finances, represent the kind of crisis that most people would see as rendering the manifesto null and void, as in effect triggering what in business would be called a "force majeure" clause?If so, it has happened through a period of mystical silent osmosis, from Johnson's private thoughts to voters' preferences, since the prime minister has not yet even attempted to make the case for why he should not be held to his election promises.Strikingly, I cannot find a single member of Boris Johnson's cabinet who argues national insurance should rise.
Instead, most of them point to the much faster than expected decline in monthly government borrowing (year-to-date borrowing is already more than £26bn less than the Office for Budget Responsibility forecast in March) and they argue there is therefore time to make a more considered assessment of whether this tax on people and employers needs to rise.Those ministers have three concerns.Perhaps the most important one is that the prime minister does not appear to be able to say with any precision what the £10bn is for.On the one hand, it is supposed to put the social care system - long-term care for the elderly and frail - on a sustainable financial footing.Which would be all very well, except there has been no published government report on Johnson's watch of the social care sector's needs, despite his assurance that such a plan exists.Second, most of the new billions will be going in the first few years to the NHS, to help it catch up with the backlog of millions of operations, procedures and treatments, that have been delayed by the invasion of Covid-19.This does not look like laser-like targeted help, a rare example of benign hypothecation. For most ministers, the NI rise is billions being poured into a huge and fuzzy health-and-care black hole, without even the fig leaf of a half-plan to ensure the money is spent properly.Third, ministers and the PM's MPs recognise that national insurance is not necessarily the fairest tax to use to raise funds for services that are predominantly of use to the oldest, since it isn't levied on those who reach retirement age, and is levied even on young people with very low earnings.This matters, given that both the financial crisis of 2007-9 and the Covid-19 crisis had the most damaging economic impact on young people, and the finances of the older generation largely improved.Johnson wants to be seen as a One Nation PM. But in taxing the young disproportionately, he looks like someone penalising younger Labour voters to protect older Tory ones.So will there be a full-scale cabinet revolt?There's circumstantial evidence of Downing Street prophylaxis against one. The rumours of a Thursday reshuffle may be the PM's Stalin-lite threat to colleagues to back him or risk demotion or even exile to the backbenches.But even without that threat, Johnson's not in serious trouble. Remember he picked his cabinet for loyalty not backbone.Johnson will get his tax. And whether he likes it or not, it will always have his name on it.
Listen to our Calling Peston podcast: