Chancellor Alistair Darling says Britain faces the toughest spending cuts in 20 years if Labour is re-elected this year.
In an interview in The Times newspaper, he said "the next spending review will be the toughest we have had for 20 years."
"Most people know that public spending has doubled over the last 10 - 12 years, so we are coming off a much higher base," he said.
"We are not talking about a situation where we have already cut to the bone."
Mr Darling also confirmed there would be a pre-election budget.
The BBC reports that this was designed to stem speculation there may be an early election.
By law, there has to be three months between the pre-budget report in December and the actual budget - making a March election all but impossible.