Iain Duncan Smith has confirmed that he is to stand for the leadership of the Conservative Party.

He called for unity and change but said that the party should not attempt to become another New Labour.

Duncan Smith said that the Conservative Party had allowed itself to be portrayed as something far removed from its core values.

"The party has allowed itself to become caricatured by our opponents as a narrow sect, but this is not in the traditions of Conservatism. Disraeli made the Conservatives the party of one nation - for rich and poor alike - more than 100 years ago. We need again to demonstrate that the party is open to all those who share our values," he said.

He warned that the party should not jettison its core beliefs, but should instead champion core Tory values.

"The future of Conservatism lies in our beliefs and values, not by throwing them away. We need to shed associations that bind us to past failures, but hold faith with those things that make us Conservatives. There is no future for the Conservative Party in attempting to be more like New Labour. We should not try to out-Blair Mr Blair. The Conservative Party must accept the need for change. We must broaden the base and the appeal of the party," he said.

But he admitted that there was a wider issue of apathy among the public which would have to be addressed. "The election defeat was a bitter blow to the Conservatives, the low turnout is also a signal of the despair people feel about the political process under Mr Blair and the Conservatives must challenge the cynicism of this Labour government," Duncan Smith said.

Duncan Smith, a staunch euro-sceptic, offered a potential olive branch to pro-Europeans on the left of the party.

"I recognise that there is a minority in the Conservative Party who take a different view and who may wish to campaign for entry into the euro. The party must be able to manage the difference and do so in a mature way. I want frontbenchers to be able to serve on the understanding that as and when the referendum comes, those who disagree with the party line can temporarily stand down and campaign for the euro," he said.

Duncan Smith paid tribute to William Hague, calling him "a man of outstanding determination, courage and principle" adding "He has left us with much to build on and much to be proud of".

Duncan Smith: The Man

A darling of the Thatcherite right he is the man credited with the "demon eyes" poster used against Tony Blair in 1997.

Strongly eurosceptic, Duncan Smith, 47, is the bookies' second favourite to succeed William Hague.

Scottish-born, he entered the House of Commons in 1992 - replacing his vocal supporter and ideological soulmate Norman Tebbit as the MP for Chingford.

Despite being seen as a potential highflyer, the former Scots guards officer refused to enter the Major government as a result of his fervent opposition to the Maastricht Treaty.

He is close to Martin Howe, the eurosceptic QC and constitutionalist who held a string of clandestine meetings with cabinet ministers in the dying days of John Major's administration.

A supporter of John Redwood in 1997, Duncan Smith was deeply unhappy with Redwood's decision to back Ken Clarke after he was eliminated from the election process.

Whilst Redwood swung behind Clarke's bid, Duncan Smith parted with his leader and opted to join the Hague camp.

Despite claiming that he would "keep his own counsel" over Redwood's decision, it is rumoured that his decision to switch to Hague resulted in several Redwood supporters following suit.

After Hague's victory, his decision was vindicated when he was rewarded with a job on the frontbench, becoming shadow social security secretary.

During that time he built on his right-wing credentials. His pamphlet, "Who Benefits? Reinventing Social Security" called for a radical rethink of welfare spending.

After two years with the social security brief, he cashed in on his military credentials by becoming shadow defence secretary.

In that role he led the Tories' opposition to gays in the military and expressed strong disquiet at women serving in the frontline. He also led an effective attack on the government over the operational capabilities of the armed forces and is an outspoken critic of the European rapid reaction force.

He also sought to emphasise his "commonsense" approach by dismissing proposals to give servicewomen breast implants as "ridiculous" saying it brought a whole new meaning to the phrase "second front".

Whilst he has admitted that the Tories will need to re-evaluate their approach he is stressing that he would provide continuity with the Hague era.

Speaking yesterday he said: "What the Conservative Party needs is to make sure there is continuity and change. They need somebody to lead them who wants to do the job and can harness both those aspects."

He has handed an olive branch to pro-Europeans, saying he wanted to heal the rift over Europe. "It is an issue that we now need to find a way of bringing the party back together around it,'' he said.

However he remains the most eurosceptic of the three likely candidates to seek the party leadership and will prove potentially unacceptable to senior Tories such as Chris Patten and Douglas Hurd.

He is likely to win the backing of Baroness Thatcher, who is reported to have identified him as a future leader. He forms a close-knit group of younger Tory MPs, including Bernard Jenkin, who are said to meet regularly with the former prime minister in her Belgravia home.

Tory modernisers will oppose his leadership, believing that he was one of the "right-wing moralists" in the shadow cabinet who "bullied" William Hague into putting a three-line whip on the Clause 28 vote in a bid to embarrass Michael Portillo.

John Major is said to be against Duncan Smith's leadership ambitions - holding a lingering resentment over his decision to turn down a government post to continue his European war of attrition from the backbenches.

Other Tories fear that his lack of voter recognition and his Thatcherite views will work against Duncan Smith - with some expressing fears that by selecting him the party will plump for "William Hague's lesser known big brother".

Clean Sweep

His campaign is likely to be fronted by Jenkin - the right-wing shadow transport minister.

Speaking over the weekend, Jenkin extolled the straight-talking virtues of the shadow defence secretary.

"We need someone who can lead the whole party. What we are looking for from the leader of the Conservative Party is someone who is going to jettison past mistakes. We are not going to win the next election trying to out-Blair Blair and coming up with similar policies. We have got to have different policies," he said.

"We need a clean sweep and we need a leader of the Conservative Party where what you see is what you get."

Married with four children, Duncan Smith's supporters will seek to portray him as the "family man" - in contrast with Michael Portillo who has no children and has admitted to "gay flings" in his student days.

Interviewed by the Observer he said his main ambition in life was to publish a novel. "I have a superb ambition, which is to publish my book. It's a novel which I have part written, but I never seem to get time to finish," he said.

He comes from a strong military background - his father was a squadron leader in the Second World War - and he was educated at HMS Conway cadet school. Whilst in the forces he served in Zimbabwe and in Northern Ireland at the height of the troubles. He left the forces in 1981, joining Marconi before moving to Janes Information Group where he oversaw the publication of Janes Defence Weekly.

Despite his strong right-wing credentials he had a brief run-in with the law in 1995 when he was fined £210 and banned from driving for a week by Lymington magistrates for driving at 80mph through a 50mph road works speed limit - his second speeding offence within five months.

Earlier this year he turned down an invitation to pose nude as a centrefold in Cosmopolitan magazine.