Lincoln claimed as inspiration for the Tories

As the man who presided over the end of slavery in the United States, Abraham Lincoln has an assured place in world history.

But now the 16th US president has a new – and perhaps unwelcome – claim to fame: as the inspiration for Iain Duncan Smith's Conservative Party.

Oliver Letwin, the Shadow Home Secretary, yesterday named the philosophy of freedom outlined in Lincoln's Gettysburg address as the idea driving Mr Duncan Smith's new "fair deal for everyone", which was launched in a blaze of publicity last week.

Mr Letwin outlined his case yesterday on BBC1's The Politics Show. He said: "Abraham Lincoln is an unlikely hero... but he had inner qualities of faithfulness, honesty and courage. He set out in his now-famous Gettysburg address the case for freedom and for equal rights before the law.

"When I am asked which is the politician I most admire, my answer is Abraham Lincoln, because he most clearly brings together the three things that I believe and the Conservative Party believes are the most important things: the liberty of the individual, personal responsibility and equality before the law."

But despite the high ideals espoused by Mr Letwin, his party leader faced a renewed attack from his own side. Crispin Blunt, the former Conservative frontbencher who resigned over Mr Duncan Smith's leadership, renewed his call for MPs to overthrow him as leader.

However, Mr Blunt admitted that the party "can win" with Mr Duncan Smith at the helm and acknowledged that he may fail to secure support for a leadership challenge.

He said: "We can win with Iain. The trouble is it's going to be much more difficult to win with Iain. He is not the best person to make the case for the party to the country as our leader.Now is the time to come to that judgement, to simply make the decision we need someone who is going to put our case more effectively."