Two ex-ministers called Wednesday for a ballot of Labour lawmakers on whether Prime Minister Gordon Brown should remain leader, highlighting his vulnerability months before a general election.

Brown has faced repeated rumours of a threat to his struggling leadership since taking over from Tony Blair in 2007 but has held on and will have to fight a general election before June this year.

Although the latest development seems unlikely to unseat Brown, it is deeply embarrassing and makes public the splits which have dogged Labour for most of his premiership.

'Deeply divided' 

NONEIn a letter to all Labour lawmakers, Geoff Hoon (right) -- defence secretary when Britain joined the Iraq war in 2003 -- and former health secretary Patricia Hewitt said the party was "deeply divided" over whether Brown should be leader.

"Many colleagues have expressed their frustration at the way in which this question is affecting our political performance," they wrote.

"We have therefore come to the conclusion that the only way to resolve this issue would be to allow every member to express their view in a secret ballot."

If there was no secret ballot, this "grumbling" could continue into the election campaign, diverting attention from "our real message", said Hoon and Hewitt, seen as Blair allies.

The letter gained early support from a handful of persistent Brown critics who say that, with Labour around 10 points behind the main opposition Conservatives led by David Cameron, it is time for a change.

Its timing is awkward -- parties effectively started election campaigning this week after the Christmas break. Brown has not yet called the general election but it looks likely to come in May.

It seems improbable that any vote, which could come as early as Monday, would go against him, not least because there is no obvious candidate to replace him.

But if it did, it could allow figures like Foreign Secretary David Miliband -- who reportedly considered standing against Brown in 2008 -- a way to challenge for the leadership without having wielded the knife.

In a brief statement hours after the letter was released, Miliband said he "supported the re-election campaign for a Labour government".

"I am working closely with the prime minister on foreign policy issues and support the re-election campaign for a Labour government that he is leading," he said.

'Lukewarm' support

British news media suggested Miliband and other key cabinet ministers were offering only "lukewarm" support for Brown, given their comments and the length of time taken to make them.

The Times described Miliband's statement as "less than wholehearted," while The Guardian said it was "both later and less full-throated than anything offered by fellow cabinet members."

The BBC reported six cabinet ministers were prepared to support a coup.

NONEIn June last year, Brown fended off a nascent leadership plot after several Cabinet ministers quit in quick succession and one, James Purnell, urged him to step down.

Westminster rumours that another cabinet minister could be about to call publicly for Brown to quit in the coming days have so far proved unfounded.

Peter Mandelson, Business Secretary and Brown's effective deputy who reportedly fell out with the prime minister in recent weeks, responded to the letter by saying the government should carry on as usual.

"No one should over-react to this initiative," he said. "It is not led by members of the government. No one has resigned from the government.

"The prime minister continues to have the support of his colleagues and we should carry on government business as usual."

Mandelson has also dismissed the reports of a resignation.

One of Brown's closest allies, Schools Secretary Ed Balls, dismissed the call for a ballot, saying it would make voters think Labour had "lost our marbles".

"The government, the Cabinet, the Labour Party is fully behind Gordon Brown," Balls told Sky News television. "I've spoken to the prime minister but he's getting on with doing his job."

-AFP