David Cameron vowed he would "not roll over and let Ed Miliband and Alex Salmond wreck" the economy as he acknowledged the Tories have a "fight on our hands".

With just 10 days to go until the election, the Conservative leader set out his plans to help the small businesses he said were the "backbone" of UK plc.

In an impassioned speech in London, he said the economy was "everything" - it was the "good school we want our children to go to" and "the hospital bed we want", he claimed.

The Prime Minister said Labour referred to business as a "predator" but added that this was "not an Arnold Schwarzenegger movie".

After a weekend in which Mr Cameron faced criticism the Tory campaign was lacking and failed to convey any positive ideas, he spoke about being "pumped up" and having a "fight on our hands".

He said: "If you think I am going to roll over in the next ten days and let Ed Miliband and Alex Salmond wreck that you’ve got another thing coming.

"We have got a fight on our hands and we are going to win that fight."

When asked if he had left it too late to start giving more animated speeches he said: "If I'm getting lively about it, it's because I feel bloody lively about it."

He said Britain was "staring down the barrel" of higher taxes and regulations for businesses if Labour wins on 7 May.

It comes after 5,000 of the country’s 5.2 million small businesses signed a letter to the Daily Telegraph saying the they "would like to see David Cameron and George Osborne given the chance to finish what they have started".

Writing in the Telegraph Baroness Brady, the Tories' small business ambassador, said: "More than 5,000 people who run small businesses have put their names to this letter - and for three reasons.

"First: they see that Cameron's plan is working for them and their family. The second reason they've signed is the Conservatives' plan for the future.

"In the past 18 months I have been consistently impressed by George Osborne's drive to make things easier for small businesses.

"The third reason they have signed is, frankly, horror at the alternative. We are looking down the barrel of a truly terrible outcome: Ed Miliband in government propped up by the SNP, undoing all the hard work of the past five years."

A similar anti-Labour letter from big business appeared on the Telegraph's front page at the beginning of the month. It was orchestrated by Conservative co-chairman Lord Feldman.

The new letter has also been linked to Conservative campaign headquarters.