Chancellor Alistair Darling has promised a “sensible, workmanlike” Budget as he renewed his message that there would be no pre-election giveaways.
Better-than-expected tax and borrowing figures have given the Chancellor more leeway than anticipated - up to £12 billion, according to experts.
But he said voters expected him to be realistic about the UK’s precarious economic recovery and prioritise measures to stimulate growth in Wednesday’s statement.
“There is no question of giveaways. The mood of people just now is that they want to see a sensible, workmanlike Budget, a Budget for the times in which we live.
“A Budget for ensuring that we secure the recovery - because we are not out of the woods yet - but, crucially a Budget for the future,” he said.
Measures would be “focused on growth” - notably unlocking private investment - he said, with the unemployed also tipped to be offered extra help.
Mr Darling also insisted that Labour would not hold a second budget if it won the general election, dismissing Tory claims that this week’s set piece would be “window dressing”.
The Tories believe faster action is needed to cut the deficit and would hold an emergency Budget within 50 days of taking office, at which they have not ruled out making tax rises.
Shadow chief treasury secretary Phillip Hammond said: “I hope Alistair Darling will set out a Budget which is prudent, a Budget for growth in Britain.
“But the real issue is whether Alistair Darling’s Budget counts for much.
“We all know that even if Labour were to win the election, Alistair Darling would not be the chancellor.
“We don’t know whether Labour would hold another Budget after the election so this may just be a piece of window dressing we get on Wednesday.”
But Mr Darling insisted there would be no such second budget if Labour defied the polls and secured a fourth term at the election - expected to be on May 6.
There would be a Departmental spending review this year, he said. “but the two events - the Budget, the Pre-Budget Report - that is not going to change.”
Mr Darling will use Wednesday’s Budget to set out the Government’s support for a bank tax if a deal can be struck to introduce it globally.
And he claimed Tory plans to introduce a bank levy without international support if necessary posed “a hell of a risk” to City jobs.
Opposition leader David Cameron vowed to press ahead unilaterally to recoup money for taxpayers and protect them from future shocks.
Mr Hammond - who last month said any levy would have to be part of a global deal - defended the change of stance.
“It has become clear that this is now going to happen - the US is going to introduce a banking levy, Sweden has already done so, the consensus is growing - and at some point you have to make a decision to take some leadership,” he said.
If the UK had to act before America, the levy would be set at a “significant lower rate” that would not be “a major impediment to the competitiveness of British banks”, he said.
The Chancellor was urged by Liberal Democrat leader Nick Clegg not to postpone a planned 3p rise in fuel duty in the Budget.
“We have always said that over time of course you need to make sure that the fuel we put in our tank reflects the kind of environmental damage of people driving around - but you have got to do it sensitively,” he added.