Chancellor Alistair Darling must choose between country and party, George Osborne has said.
The shadow chancellor told the BBC his opposite number was "probably not going to be in post whoever wins the election" as he prepared for next week's pre-election Budget.
Mr Osborne said Mr Darling has a "very difficult judgement to make about whether he puts his country before his party".
The Conservatives want the government to address Britain's large public spending deficit by beginning to address the problem immediately.
Failing to do so, Mr Osborne warned in an article in the Financial Times co-written with economist Jeffrey Sachs, will prolong current economic stagnation by "creating fears about future debt burdens".
Labour and the Liberal Democrats believe quick cuts will put the recovery at risk, however.
"I think the central point we have to understand here is that the debt is holding back the British recovery, and unless we get confidence into the British recovery - and that comes from dealing with our debts - then we will not be creating the jobs that we all want to see," Mr Osborne told the BBC.
He wants a medium-term fiscal framework to be adopted, matched by improvements in the delivery of public services and "a decent regard for the long-term investments needed to rebuild an economy crushed by the bubbles of wishful thinking".