British Prime Minister Gordon Brown fought to defeat a leadership challenge Wednesday from two senior figures in his Labour Party, months before a national election that disaffected Labour supporters believe the party is sure to lose.

Two former members of Brown's Cabinet sent a letter to fellow Labour lawmakers calling for a secret ballot on Brown's leadership. Geoff Hoon and Patricia Hewitt said in the letter that grumbling about Brown's performance was dividing the party at the worst possible time.

"Many colleagues have expressed their frustration at the way in which this question is affecting our political performance," they said in the letter, which they released to the media. "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," it said, referring to the Labour lawmakers.

Hewitt said the letter was "not an attempted coup," but would not say whether she would back Brown if a vote were held.

Labour officials and Brown allies moved quickly to quash the rebellion.

The Labour party said in a statement that "there is no provision for a secret ballot of MPs within the Labour Party constitution or rules."

Brown's supporters said a leadership vote would make the party look divided and dash any hopes of an election win.

Former Foreign Secretary Margaret Beckett said the letter was "diversionary, it's stupid and I hope no one will pay any attention to it at all."

Tony Lloyd, who chairs the Parliamentary Labour Party, said there was "very little support" for Hoon and Hewitt's move.

Britain must hold an election by June, and opinion polls give the opposition Conservatives a big lead over Labour, which has been in power since 1997. Brown's opponents within Labour say his lackluster performance will ensure electoral defeat.

Unseating Brown would mean a quick party leadership contest and send an untested leader into a national election.

Brown replaced Tony Blair when he stepped down as prime minister in June 2007, and Brown has never faced voters in an election as leader. Many within his party doubt the taciturn Brown has the popular appeal to win. Opponents say Brown is tainted by the economic crisis — he was Treasury chief for 10 years until 2007 — and by a scandal over lawmakers' inflated expenses that outraged the public.

Brown already has faced a series of challenges to his authority from within a fractious Labour Party.

Most dramatically, in June he saw a flurry of Cabinet resignations designed to encourage a rival contender to challenge his leadership. The most likely successors — Foreign Secretary David Miliband and Home Secretary Alan Johnson — backed Brown, and that rebellion fizzled.

Hoon held several Cabinet posts, including defense secretary until quitting last year. Hewitt is a former health secretary who has said she will not run for re-election.

Conservatives were quick to capitalize on Wednesday's letter. Party Chairman Eric Pickles said it was "irresponsible to have such a dysfunctional, faction-ridden Labour Party running the country."

"We cannot go on like this," he said. "The only responsible thing the government can do is call a general election."