Thatcher backs Mr Duncan Smith

On his first campaign visit to Wales, he is expected to tell members that a vote for him would boost the party's electoral representation in Wales.

The party has failed to return any Conservative MPs in the past two general elections.

Mr Duncan Smith's tour will take in St Asaph in north Wales, Brecon in mid Wales, and the Welsh Assembly in Cardiff.

A planned appearance in Monmouthshire was cancelled at the last minute .

But Mr Duncan Smith's campaign team have said that this will have no bearing on his support among the Welsh membership - which they insist is extremely favourable.

A key theme for the shadow defence secretary's tour will be agriculture.

It is one of the worst kept secrets in politics that he is the chosen heir of Mrs Thatcher and Norman Tebbit

Ken Clarke

He is expected to say too that unlike his rival Ken Clarke he can unite the party and revive it's electoral hopes in Wales.

Mr Duncan Smith's visit comes on the day that leadership ballot papers begin to drop on to the doormats of up to 15,000 Conservative members in Wales.

It also coincides with Lady Thatcher throwing her weight behind Mr Duncan Smith in the leadership contest, saying Ken Clarke would steer the party to "disaster".

In a letter published in Tuesday's Daily Telegraph, Lady Thatcher says the Conservatives would be deeply split under Mr Clarke, whose views have "had their day".

But Mr Clarke has hit back, saying the agenda advocated by the former prime minister would turn off young people and floating voters.

'Learn election lessons'

Mr Clarke said that Lady Thatcher's support for Mr Duncan Smith came as no surprise.

"It is one of the worst kept secrets in politics that he is the chosen heir of Mrs Thatcher and Norman Tebbit," he told BBC Radio 4's Today programme.

The former chancellor continued: "Nothing is more likely to turn off young people and floating voters from the Conservative Party than the knowledge that we are going for the kind of agenda that Mrs Thatcher seems determined to force us on now.

His rival, Mr Duncan Smith, welcomed Lady Thatcher's intervention and denied it would "horrify" some voters.

'Great leader'

"I welcome it obviously. I didn't, to be quite frank, expect her to come out quite so clearly, but I welcome it," he said.

"People will remember her as a great Conservative leader, who led us to a series of victories."

On Monday, the two challengers for the Conservative Party leadership set out their stalls in detail for the first time as the contest entered its final phase.