Jonathan Reed: If they are to regain our trust, politicians must play fair with their poll promises

As candidates fan out for a final flurry of door knocking and leaflet posting now the election campaign is finally underway, their chief challenge is not persuading the public to vote for them ahead of their rival – but to convince them it is worth voting at all.

Yet that trust must be earned rather than assumed – and at the moment there are worrying signs that the message is not sinking in.

Recently, Labour published a dossier claiming the Tories have

a "credibility gap" when it comes to their plans for the economy – but all three major parties are running the risk of failing some of the

basic tests required to restore public trust.

Take the economy. Both parties have been keen to boast of their "efficiency" savings, yet with little evidence to convince voters that either of their sums add up.

On Budget day, Labour promised 11bn of efficiencies divided between Whitehall departments. It sounded good at the time – and some of the measures were indeed worthy of consideration – but closer scrutiny revealed vast sums accounted for in bland platitudes.

Take the Department of Energy and Climate Change sticking its neck out on the line by finding "further savings... from efficiencies found by arms' length bodies", or the Department of Communities and Local Government promising 70m by "seeking opportunities to deliver better value for money and produce savings including through rationalisation and reform as appropriate". Such vague comments leave us none the wiser about the impact that such "efficiencies" would have on services and the budget.

The lack of detail quite rightly brought criticism from opponents and observers – with Shadow Chancellor George Osborne claiming Labour has "never been serious about tackling waste and inefficiency".

A few days later, Mr Osborne unveiled Tory plans to halt next year's National Insurance increase – justifiably popular, particularly with businesses, and potentially a real vote winner – based on finding 6bn of savings which fall foul of exactly the same criticisms of vagueness.

Promises of renegotiating contracts are all very well, but how can the Tories know how much this will save until the deed is done? Reducing public sector property costs is the right approach, but how much money can be saved in 11 months? And not filling vacancies sounds painless, but while it may not mean making people redundant it surely also means having more people out of work, something the party is much less up front about.

On their use of statistics, the two parties fare little better.

The Prime Minister's knuckles are still red from the rapping

administered by statistics adjudicator Sir Michael Scholar, chairman of the UK Statistics Authority, after quoting misleading immigration figures. And that came just weeks after being forced to admit giving misinformation to the Chilcot Inquiry over defence spending.

But manipulation of statistics is not just a Labour disease. Sir

Michael had cause to criticise Shadow Home Secretary Chris Grayling recently for comparing violent crime statistics which were not

comparable to paint a bleak picture of Labour's record on crime. And last year they were happy to attack the Government's record on malnutrition among hospital patients using figures which contained a clear health warning saying they should not be compared in such a way.

And on tax, Labour is happy to suggest the Tories will send VAT soaring if they win the election – Lord Mandelson, the Business Secretary, last week described the sales tax as the "age old Tory tax hike" – without ruling out such an increase themselves.

In fact, both parties are happy to insist they have no plans to

introduce such an increase, but cynical voters are entitled to worry that while there may be no such plans today that does not rule anything out tomorrow.

Indeed, both Mr Osborne and Alistair Darling insist that no Chancellor would rule out tax changes. Yet Labour is happy to guarantee in its manifesto that it will not raise income tax – the same pledge, incidentally, from its last manifesto that it breached at the start of this month when increasing the new 50p tax rate.

Meanwhile, for all their talk of building a new kind of politics, the Liberal Democrats seemed to resort to classic old tricks through their attempt to frighten voters away from David Cameron with their recent billboard decrying a "Tory VAT bombshell".

The official election campaign may only be a week old, but after months of phoney war the parties have left themselves with a mountain to climb if they are to begin regaining the public's trust.

In the wake of the expenses scandal, party leaders have all talked with passion of their desire to clean up politics. Playing fair when it comes to campaigning must be a vital part of that process.

Jonathan Reed is the Yorkshire Post's political editor.