'Gordon is like a Damien Hirst sheep trapped in formaldehyde,' says MP as Brown makes desperate call for unity

Gordon Brown has warned the global financial crisis 'is not the time for faint hearts' as he issued a defiant plea for Labour unity.

The Prime Minister tried to calm feverish rumours about his future by insisting it would be for the voters - not MPs - to judge if he has failed.

He told Labour plotters the financial turmoil required an experienced leader in No 10, saying: 'This is the time for people who know how to deal with difficult economic circumstances.'

He added: 'I am not going to be diverted by a few people making complaints.'

He claimed his ordeal of losing an eye as a teenager had taught him to 'fight back' against adversity.

He also denied his 'good friend' Tony Blair was behind the plotting against him, saying: 'I talk to him regularly.'

But another day of febrile speculation saw one ministerial aide admit more ministers could resign in protest at his leadership.

There were growing signs that the Cabinet is losing patience with the Prime Minister in the face of polls showing Labour on course for an election disaster.

Labour MP Alan Simpson predicted the party conference next week would be Mr Brown's last as leader. 'Gordon is like a Damien Hirst sheep,' he said.

'Trapped in formaldehyde, he lacks the qualities needed for a bold leap that would free him from his own goo.'

Mr Brown used a wide-ranging interview with Sky News to confirm that his strategy for political survival is to ignore calls to quit and emphasise his economic experience.

'This not the time for faint hearts,' he said, adding: 'It is easy to think in a difficult economic time that you bail out.'

He tried to play down the chaos engulfing his leadership as a temporary difficulty.

'I have been in politics a long time. You go through periods,' he said.

'Sometimes you are popular, sometimes people resent the decisions you make and sometimes people are disappointed. You always get that.

'You take the rough with the smooth. You deal with the problems you face.'

Challenged that voters have no clear idea about why he wants to be Prime Minister, Mr Brown acknowledged for the first time that his premiership could end in failure.

'I could have done anything else,' he said.

'I felt public service could make a difference to our country. I felt I could do service in this way.

'If it turns out that that is not the case then that is for the people to judge. I am trying to do my best for the country.'

Unflattering comparison: Brown has been likened to Damien Hirst's sheep trapped in formaldehyde artwork

He added: 'Everybody knows I went through a period when I almost lost the sight in my eyes and I had a very difficult time.

'That only makes you stronger and more determined and more resolute to go on with things that are important.'

Mr Brown lost the sight in his left eye as a teenager playing rugby.

MP Roberta Blackman-Woods accused those who have protested over his leadership of trying to 'destabilise' Labour.

The parliamentary aide to Defence Secretary Des Browne said Mr Brown and Labour should focus on the job of governing.

But she told the BBC: 'It may be that there will be other resignations.'

There was more trouble for the Prime Minister when a poll of Labour members found more than half want him to stand down.

The survey for the Independent by the activist website Labourhome.org found 54 per cent wanted someone else to lead the party.