Cameron predicts tight election but warns that hung Parliament will damage Britain

The Conservative leader said that the country needed the forthcoming general election to deliver a strong government capable of taking long-term decisions for the future.

Despite the latest opinion polls showing the Tories widening their lead over Labour, he acknowledged that the result would be "tight".

Nevertheless he insisted that an outright Conservative majority was "do-able" and he refused to be drawn on the possibility of a post-election pact with the Liberal Democrats.

"I am hoping to win the election outright. I think that is absolutely do-able and deliverable. That is what I am shooting for," he told Sky News's Sunday Live with Adam Boulton. "It is a challenge. It is a tight election. It is going to be very close. People have a real choice.

"We are fighting for an overall majority, we think that would be best for Britain. We think a hung parliament would be damaging; the uncertainty would be bad for Britain. We need a decisive government that can take long-term decisions. That is what we want to deliver."

Mr Cameron defended Tory plans to reverse part of the Government's planned increase in national insurance contributions in the face of Labour claims that it could not be afforded.

He said that it would be paid for through 6bn of efficiency savings in the current year.

"This is not a tax giveaway. This is just stopping one of Labour's tax rises and saying, frankly, 'They have got it wrong'," he said.

"We will be borrowing and spending less than Labour would in 2010 and that enables us, not to stop all of the tax rises, but to prioritise as progressive Conservatives the tax rise that hits the economy, that hits jobs."

He dismissed suggestions that business leaders who backed the plan were "Tory stooges" but did not rule out the prospect that some could in future be awarded peerages by a future Conservative government.

Mr Cameron admitted he was "nervous" about the forthcoming televised leaders' debates and acknowledged that they represented a risk for the Conservatives. Nevertheless he insisted it was the right thing to do.