Campaign: We are the true party of change say Conservatives

Amid concern about the sudden rise in popularity for Liberal Democrat leader Nick Clegg, Mr Cameron said the public was "grabbing on to anything new" in an attempt to find a different direction for Britain but warned that there was a risk the country could end up mired in "uncertainty, fudge and division".

It came as Shadow Schools Secretary Michael Gove, on a campaigning visit to key marginal constituencies Pudsey, Leeds North West and Keighley, said Mr Clegg had been the "new kid on the block" during last week's first televised leaders' debate but insisted Mr Cameron had "outclassed" Gordon Brown as Labour and the Tories continue to spar over who performed best.

Mr Gove insisted all parties will find their policies under fresh scrutiny but said he was confident the Tory proposals for a Big Society would appeal to voters.

"It's clear now there's a strong appetite for change – you've seen Labour at its lowest point for some time," he said.

"There are basically two avenues for change – people can either vote Liberal Democrat or vote Conservative. I'm convinced that as the campaign goes on you will see more and more people appreciating if you vote Conservative you're guaranteed a strong government at a difficult time."

Mr Gove said some Labour MPs in the region had been "servants of the Labour machine rather than champions for their community" and insisted Tories would be very different.

Campaigning in south London, Mr Cameron said voters were "crying out for change" and vowed to "redouble the positive".

"I am going to accentuate everything positive we want to bring to this country," he said.

TV broadcast changes tack

David Cameron shelved a party political broadcast attacking Labour in favour of one that "responds to the public mood".

The video scheduled to be aired yesterday evening was replaced with a "personal statement" from the Tory leader in which he detailed his values and qualities.

The tactical change was made as the scale of the Lib Dem "bounce" after the first prime ministerial debate became clear.

The last-minute move is evidence of the depth of concern among senior Conservatives over the impact of Nick Clegg's much-praised performance.

Two polls have now recorded the Lib Dems surging into an overall lead for the May 6 election.