London, July 26 : British Prime Minister Gordon Brown was told that he has only 42 days to turn around Labour’s fortunes or face an autumn leadership crisis.

The warning came after the party slumped to one of its all-time lows with a crushing by-election defeat.

Labour plunged into turmoil when it was trounced in Thursday’s Glasgow East by-election.

The party’s 13,507 majority was annihilated by the Scottish National Party, which took the seat with a 22 per cent swing.

That — repeated in a general election — would have catastrophic consequences for Labour, with Brown and most of his Cabinet losing their seats.

The party was rocked again last night when a poll showed that David Cameron’s Tories had opened up a massive 22-point lead over Labour.

That would be enough to put the Conservatives in power with a majority of 236.

Brown would go with a swing of 21 per cent, The Sun reported.

A repeat of voting patterns in May 2010 would see David Cameron in No10 with a massive majority.

Conservative leader Cameron challenged Brown to call a general election on Friday after the SNP''s sensational win over Labour in the Glasgow East by election.

The ComRes survey gave the Tories the support of 46 per cent of voters — the same as last month — while Labour had slipped to 24 and the Lib Dems were unchanged on 
18.

Brown has been told he will face a Cabinet revolt unless he can lift his party out of the doldrums well before the end of September.

But the defiant PM is prepared to take on all-comers — insisting he is the right man to lead Britain through its economic crisis.

Brown sought to steady Labour nerves with the assurance that he was "getting on with the job" of leading the British people through difficult economic times. (ANI)