Brown shock as support for Tories passes 50% for first time since 80s

An Ipsos MORI poll published today showed the Tories up four points on 52 per cent.

The news comes amid reports that another member of the government is set to quit within days over Mr Brown's leadership.

Eric Joyce, the Falkirk MP and parliamentary private secretary to John Hutton, the Business Secretary, is reportedly considering resigning after the Labour conference which begins this weekend.

And James Purnell, the Work and Pensions Secretary, added to Mr Brown's woes when he said in an interview with the New Statesman that it was "ridiculous" to condemn colleagues who voiced concerns.

"I think it would be ridiculous to pretend that you can't complain when you're worried," he said.

"I mean, I'm worried that we're 20 points behind (in the polls].

"I'm not going to condemn people or question their motives. (But] I don't agree with what they did," he said, referring to their call for leadership nomination papers.

Mr Purnell, who is tipped as a potential future leader, also refused to rule out supporting a future leadership challenge, saying merely that the question was "hypothetical".

The spate of critical outbursts which follow the resignation of David Cairns, the Scotland Office minister, have threatened to overshadow Labour's conference in Manchester.

And the eve-of-conference poll gives the Conservatives the biggest lead since August 1988, a year after Margaret Thatcher's third election victory. The survey shows the Tories are up four points since a similar poll last month, Labour unchanged on 24 per cent and the Lib Dems down four to 12 per cent.

The result undermines the Liberal Democrat leader Nick Clegg's attempts to rebrand his party as a tax-cutting challenge to the Tories after a week of media coverage at his party conference in Bournemouth.

People also have a more positive attitude towards the idea of a Tory government, as opposed to simply being tired of Labour, with 54 per cent of those questioned agreeing that Mr Cameron's party was ready to govern – up 19 since last month.

Another embarrassing resignation could be around the corner, however, after Mr Joyce was reported to be considering quitting after the Glenrothes by- election.

It came after a TV interview yesterday, when Mr Joyce offered muted support for Mr Brown when asked if he backed a leadership contest.

"Gordon is going to make a big important speech on Monday and lay out his vision and then we're going to go and win the Glenrothes by-election," he told BBC Scotland's Holyrood Live.

Asked if Mr Brown categorically had his 100 per cent support, Mr Joyce added: "It's absolutely essential that we are unified and see what Gordon has to say on Monday."

He later told The Scotsman: "I have no intention of resigning as PPS to John Hutton. I support Gordon Brown 100 per cent for conference and the Glenrothes by-election."

Asked if he would quit if Labour lost, he said: "It's not a question I can consider. I'm confident we will win."

Earlier, Defence Secretary Des Browne had warned would-be dissenters that there was "no alternative" to Mr Brown.