Mr William Hague stole a march on the other parties yesterday with the early publication of the Conservative Party's £8 billion tax cutting election manifesto.
But he was joined in an instant tax and spending battle by Labour and the Liberal Democrats. Labour branded the Tory proposals "a deceit", while the Liberal Democrat leader, Mr Charles Kennedy, claimed they were unravelling.
Mr Tony Blair set off for the first time on his election "battle bus" bearing the slogan "The Work Goes On", buoyed by yesterday's Bank of England cut in interest rates, and declaring himself happy that the electorate would judge his government by the credibility of its performance and its promises.
Before setting out from a capital bathed in brilliant sunshine, the Prime Minister hosted Labour's first election press conference, declaring the most important change in recent years "the fact that Labour enters this election as the party of economic competence".
He said: "We cannot afford to risk the stability we have gained and the progress we have made. The people will judge the credibility of our performance and our promises - and I welcome that."
He insisted: "The choice between us is fundamental. Stability and opportunity or a return to 15 per cent interest rates and negative equity. Record investment in schools or hospitals or cuts in public services. The targeted, affordable tax cuts we have made or irresponsible tax cuts that would threaten a return to boom and bust."
The heavily trailed proposal for a 6p cut in the price of a litre of petrol was the headline-grabbing element in the Tory tax cutting package targeted at pensioners, savers and married couples.
Trumpeting the traditional Tory theme of liberating people and allowing them more control, Mr Hague said the choice in the election was "between a Labour Party that trusts government instead of people, and a Conservative Party that trusts people instead of government".
The Chancellor, Mr Gordon Brown, condemned the Tory plans, insisting they would cost £16.6 billion in the first three years alone, with promises on top of that of cuts in inheritance and capital gains tax and top rate tax relief on private medical insurance.
"These are irresponsible tax promises that put stability at risk and threaten schools, hospitals and mainstream public services," he declared.
While dismissing the Tory petrol price cut as "a stunt", Mr Kennedy also claimed Labour could not hope to meet the aspirational five pledges unveiled on Wednesday, having failed to meet the more realistic targets set in 1997.
Plaid Cymru, meanwhile, claimed Labour's "Tory economic policies" had created boom in the south-east of England but bust in Wales. Plaid's policy director, Mr Cynog Dafis, claimed the government's refusal to use taxation as a tool to control inflation had led to high interest rates damaging to the Welsh economy.
The Institute of Fiscal Studies has warned that Labour will need higher borrowing or tax rises of £5 billion a year by the end of the next parliament to sustain the rebuilding of public services at the current rate.