Conservative leader David Cameron has refused to say if he would raise taxes if he becomes prime minister.
Speaking on BBC One's Andrew Marr show, Mr Cameron said he was not prepared to write the budget for 2010 now.
He said a "different approach to government spending was needed", adding he would "always do what is right" to "ensure strong public finances".
Last week Lib Dem leader Nick Clegg said he favours a tax-cutting programme for people on low and modest incomes.
During an interview with Andrew Marr, the Conservative leader was challenged about whether he would cut spending, increase borrowing or raise taxes to cope with the economic difficulties his government would inherit.
"I think it is completely unrealistic to ask, possibly two years before a general election, when we're only a few months into this financial year," said Mr Cameron.
He said there was a need for an approach to government spending that "cut the costs of social failure" and reforms public services "because unreformed public services cost more".
But, when pushed on whether he would raise taxes, he said: "You have to look at everything, but I'm not going to write my budget for 2010 now."
The Conservative leader said he was being asked to write his budget for 2010 when the government "haven't even finished writing their one for this year", adding that Labour's was in the process of "falling apart".
He said it was easy to make promises while in opposition and he argued that the Conservatives, under his leadership, avoided such tactics.
However, he said his party's economic plans would be revealed before the next general election.
BBC political correspondent Vicki Young said: "The economy is the dominant issue for all politicians at the moment.
"It's very interesting that when it comes to the Tory party, most people think of them as a tax-cutting party.
"Many on the right, when David Cameron became opposition leader, were pushing him to announce that he would cut taxes when he came into power. He very strongly resisted that, saying that he didn't want to disappoint people with things he couldn't deliver."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.