The National Party's deputy leader Bill English has told a business election forum it will be difficult to slow the increase in government spending.
National has promised to cut back the rate of government spending.
Mr English told the Business New Zealand forum in Wellington that government spending has been increasing at 8% a year and that cannot continue. However, he says slowing that increase will be a big challenge.
Mr English says it is clear that when the Treasury releases the pre-election fiscal and economic update, it will show the Government's books are in the red.
ACT Party finance spokesman Sir Roger Douglas says the more a government spends, the more it has to tax its citizens.
Earlier, Prime Minister Helen Clark told the forum her government had an ambitious set of policies to promote economic growth.
New Zealand First leader Winston Peters cancelled his scheduled appearance at the forum on Wednesday.