Charles Clarke lines up southern 'stalking horses' to challenge Brown's leadership

Gordon Brown faces a possible stalking-horse challenge to his leadership orchestrated by his arch-enemy Charles Clarke, it was claimed last night.

The former home secretary is understood to be collecting names of MPs for an emergency contest if Labour performs badly in the 1 May London and local elections.

In the most serious threat so far to the Prime Minister's 10-month leadership, many Labour MPs with seats in the South who stand to lose at the next general election are at the heart of a potential revolt, insiders say. One MP claimed last night that "Charles has the names" needed to trigger a ballot. Either Mr Clarke or another MP with "nothing to lose" would stand as a way of gauging opinion in the Labour Party, the MP added.

While the stalking horse would stand no chance of winning, the scale of support for a contest could cause long-term damage to Mr Brown's leadership and eventually force a more credible challenge before the general election.

There was more bad news for Mr Brown last night as a new poll put the Conservatives on 44 per cent, a 16-year high.

The YouGov survey for The Sunday Times showed Labour trailing by 16 points on 28 per cent, with the Lib Dems on 17 per cent. The poll also showed that if Tony Blair was still leader, the Tory lead would be just five points.

Claims of a "southern rebellion" follow speculation over Mr Brown's future and who would succeed him if he stepped aside or were forced out.

In a sign of alarm within Downing Street, Labour whips sent messages to all the party's MPs warning them not to respond to surveys from the media on who they would vote for in a possible leadership contest.

The Prime Minister has been under fire by more than 30 MPs over the scrapping of the 10p tax rate which they say punishes Labour's working-class base.

Critics inside the Government complain that despite the appointment of PR man Stephen Carter to No 10, there is no over-arching strategy or direction.

In a sign of the growing unease with Mr Brown's strategy, Tessa Jowell yesterday became the first senior minister to question the axing of the 10p tax rate.

The Olympics minister, who attends Cabinet, warned the PM to listen to MPs threatening to rebel.

She told the Financial Times many of the MPs were "not the usual suspects" and were providing a "reality check" to the Government that had to be taken seriously.

The timing of the speculation coincides with Mr Brown's trip to Washington and New York this week. It emerged yesterday he risks being upstaged by Pope Benedict XVI, who will also visit the White House.

Ed Balls, Mr Brown's closest cabinet ally, is the target of discontent from fellow ministers amid claims he is jockeying for position if there is a sudden vacancy. An aide to Mr Balls last night dismissed as "rubbish" suggestions that he was lining himself up to succeed Mr Brown.

But the Secretary of State for Schools has irritated ministers by chairing cross-government strategy meetings and his involvement in policy in no fewer than five other Whitehall departments. Last week Mr Balls' and Jack Straw's offices were forced to deny claims that they had nearly come to blows during a disagreement over youth justice policy.

Mr Balls, David Miliband, James Purnell and Andy Burnham have all been tipped as potential future leaders, but none of them would become involved in any "stalking horse" plan.

Some 20 per cent of MPs – 71 of the current tally – are needed initially to back a challenge. Nominations need to be sought prior to the party's autumn conference – but the rules do not say how far in advance this would be. A contender then needs 12.5 per cent of Labour MPs, or 28, to back his or her candidacy.

A Labour MP said: "Nobody will take a decision until after 1 May. Charles is putting feelers out for him or someone else to be a stalking horse, after bad results.

"The revolt will come from the South. Charles has nothing to lose and thinks he has the numbers."

Meanwhile, the Secretary of State for Health, Alan Johnson, seemed to take a swipe at Mr Carter by warning that the Prime Minister was "not a PR man".

He gave Mr Brown "10 out of 10" for his premiership, but added: "I think in this age of, kind of, I suppose a PR age of politics, [he should] not be a PR friend, that is not what Gordon does, I am afraid. He is not a PR man, he is a serious politician."

Leadership speculation has been fuelled by a left-wing motion on the party agenda for this year's conference in Birmingham to lower the candidacy threshold to 7 per cent of MPs.