Iain Duncan Smith's leadership is again under fire following poll data showing he is failing to convince Tory supporters that he is up to the job.

More than one in three voters have not formed any opinion about the Chingford MP since he secured the Conservative leadership over a year ago.

The findings come in a MORI poll which delivers a bleak message to the Conservative leader following his party conference relaunch.

The poll discovers growing dissatisfaction amongst Tory voters following his "quiet man" speech to the Bournemouth party conference earlier this month.

For the first time, more Conservatives are dissatisfied than satisfied with the way Duncan Smith is doing his job as party leader.

The survey, the first since the conference speech trailed as the most important of Duncan Smith's career, found that only 32 per cent of those who say they would vote Conservative were satisfied with Duncan Smith's performance.

Just 18 per cent of all voters are satisfied with his leadership - with 44 per cent classing themselves as dissatisfied.

The survey has again led to speculation that his job may be on the line.

Press reports indicate that 25 MPs are prepared to spark a leadership challenge by signing a motion of no confidence in Duncan Smith.

Some MPs have speculated that Michael Portillo, who has recently returned to active Commons service after a period out of the limelight, may once again be set to make a play for the Tory crown.

Whilst several MPs are expressing their concern in private, they fear that a pre-emptive leadership challenge may alienate rank-and-file members - who under current rules make the final leadership selection.

The poll came as the Welsh secretary Peter Hain said he had "sympathy" for Duncan Smith's plight.

I have had sympathy with Iain Duncan Smith from the moment he was elected," said Hain.

"I think he has got an impossible job to do and he is not doing it very well and he would be much more comfortable on the backbenches. I'd be very happy if he stayed leader of the Conservative Party."

Whilst Central Office will read the MORI poll data with a heavy heart, the figures also make difficult reading for Tony Blair - with 49 per cent of voters unhappy with his leadership.

And nearly three quarters of the country is unsatisfied with the way Labour is running the country.

Labour supporters, however, appear to be keeping the faith with the Blairite project despite rows over PFI and the looming war with Iraq.

Seven in 10 say they are satisfied with his leadership - whilst 63 per cent say they are happy with the way his government is running the country.

Only Charles Kennedy records a positive score in the poll.

Some 45 per cent of the public are satisfied with his leadership - with fewer than one in five classing themselves as dissatisfied.