Scottish Labour leader quits
An emotional Alexander, suspended from the Scottish parliament Thursday for a day for failing to declare donations to her leadership campaign last year, said the issue had become a "distraction" from politics in Scotland.
The move came the day after a by-election defeat in Henley, south England, when Labour came in fifth place behind fringe parties such as the far-right British National Party on the first anniversary of Brown taking office.
A string of recent opinion polls suggest that Brown's Labour faces defeat at the next general election, which must take place by mid-2010.
The latest telephone poll by ComRes in Saturday's Independent newspaper gave the main opposition Conservatives, led by David Cameron, 46 per cent support compared to 25 percent for Labour on a sample of 1,007 people taken this week.
Earlier Saturday, Labour lawmaker David Marshall announced he was quitting the House of Commons because of ill-health, setting up another tricky by-election for Labour, this time in Glasgow, Scotland.
Alexander is the sister of one of Brown's closest allies, International Development Secretary Douglas Alexander.