He also appeared to let slip a strong hint that there would be no snap General Election in March by saying he believed there would be another Budget before going to the country.

The Prime Minister, in an interview with BBC’s Andrew Marr Show, made a fresh attempt to portray himself as the underdog by repeatedly referring to himself as a fighter and denied that there was dissent in his own ranks going into the campaign.

He said: “I think the Conservatives wanted an election that was essentially a referendum on Labour. Then they thought they would get a referendum on the small issues. This is an election on the big issues.”

The Prime Minister said the Tories would make the situation worse by cutting public spending too early. “I believe in an age of aspiration, of opportunity and prosperity,” he said. “I am afraid the Conservatives have gone for an age of austerity, and that means the majority of hard working families suffer as a result.

“I’ve managed this country through good times and difficult economic times and we can ­manage this country through the next stage which is returning to growth, through higher levels of growth and higher levels of employment.”

Mr Brown denied there were tensions over campaign tactics between key Labour figures, such as Business Secretary Lord Mandelson and Commons Leader Harriet Harman.

“They are both going to be playing big roles in the election campaign, and every part of this Labour Cabinet is a team, it works well, and it is a team that will be fighting an election on the big issues,” Mr Brown said.

Asked about discontent among his party’s rank and file, with former home secretary Charles Clarke reportedly organising a leadership challenge event, Mr Brown said: “I don’t really worry too much about that. The issue is not about internal debates in one party. It is about the country.”

On the UK’s £178 billion deficit, he insisted: “Our deficit reduction plan was the first in the world. It is halving the deficit in four years. We are raising your taxes to do it. You will have to pay more in the top rate of tax to do it.

“We are raising National Insurance by 1% to protect our public services so that we can still spend more on health and more on education and more on policing. We are taking the difficult decisions that the Conservatives refuse to take to halve the deficit over the next four years. If you want to halve the deficit more and more quickly you will inevitably hold this country in recession longer.”

At the weekend, David Cameron fired the starting gun on the General Election campaign, insisting he was the man to lead Britain to a brighter future.

Mr Cameron called for voters to make 2010 a “year of change”, pledging that a Tory government would unify the country and get the economy back on track.

But Ken Clarke upset some in his party when he said an incoming Tory government would be ready to put up taxes to get the UK’s deficit under control.

The former chancellor said: “It’s something that every Conservative tries to avoid.Coming out of a recession when you have such a severe deficit, you can’t rule out putting up taxes.”