The Conservatives failed to win the 2010 general election because the party lacked "economic credibility", former Tory defence secretary Liam Fox has said.
In 2007, David Cameron and George Osborne promised that the Conservative Party would match Labour's spending plans for the following three years. However in the wake of the financial crisis the Tories abandoned that commitment and signalled a Tory government would instead cut spending.
Fox, who served as defence secretary in the coalition from 2010 until he was forced to resign in 2011, told student Conservatives at the University of London on Tuesday evening that this had significantly damaged the party in the eyes of the voters.
"One of the problems we had in 2010 was on economic credibility," he said. "We had said for a long time in the run up to that 2010 election that we would match Labour's spending plans. Then we turned around and said these plans are unaffordable - at the last minute."
He added: "I think had we said earlier these plans were catastrophic and we couldn’t possibly [match Labour] it would have given us more credibility when we came to make that message."
The 2010 election produced the Conservative-Lib Dem coalition. Polls suggest Britain could be heading for another hung parliament in 2015.
The economy will be central to the election in May. And Fox said this contest was "very different" to 2010, as unlike before the economy was now the party's "strong suit".
However with less than four months until polling day, the veteran MP and former Tory leadership candidate warned the party that "sometimes we are just too clever for our own good" when it came to electoral strategy.
"We’ve spent too much of our time focusing on the people who will never vote for us rather than the people who might," he said.
"We complicate the message too much," Fox told the students. He said the party "might as well talk Swahili to voters" if it did not simplify the message on debt and the deficit and relate it to household credit card bills.
The former cabinet minister said he was "quite convinced" the Tories would win the 2015 election, but said the Tory campaign needed to target Ed Miliband and Labour, not Nigel Farage and Ukip.
"The question is whether we win it as the biggest party without a majority or whether we get over the line, that remains to be seen. That is very much in our own hands. The party has begun to focus on the task at hand in a way it has not been doing for a number of years.
"Either David Cameron is going to be the prime minister or Ed Miliband is going to be the prime minister. There is no one else going to walk into Number 10. That’s what we've got to get people to concentrate on and stop our own people talking endlessly about Ukip, because Nigel Farage is not going to be in No.10. I would be very surprised if Ukip has more than one MP."
"I can't think of any natural areas where Labour has an intellectual or emotional lead over us. I think it's just a bit of self-confidence we require to get out there and get on the front-foot and whack them. We spent far too long in close proximity to the Lib Dems. It's time we got our gloves off and recognise it’s the Labour Party we are fighting in this election, not Ukip not anyone else, this is the Labour Party."
Asked whether the prime minister should take part in televised election debates, Fox said he did not think the 2010 debates had a "huge effect" on the outcome, but agreed they were a good thing. Cameron has said he will refuse to take part in the debates unless the Green Party leader is invited onto the stage alongside Miliband, Farage and Nick Clegg.
"I think it would be great to have them. I think in the right format David Cameron would wipe the floor with the others," Fox said. "If we sort it out I'd love to see David Cameron slapping around the others leaders quite ruthlessly."