Communities Secretary Hazel Blears has become the fourth minister to quit the Government, piling further pressure on Prime Minister Gordon Brown ahead of Thursday's crunch European and local elections.
Ms Blears announced her resignation in a statement just two hours ahead of Prime Minister's Questions in the House of Commons, saying she wanted to "return to the grassroots (where I began), to political activism, to the cut and thrust of political debate".
Her statement - which came hot on the heels of Tuesday's announcement by Home Secretary Jacqui Smith that she would quit in the reshuffle expected within days - was notable for the absence of any expression of support for the Prime Minister or gratitude for having served under him.
Tories said that the timing of the announcement, just 24 hours ahead of elections in which Labour was already expected to receive a mauling at the hands of voters, appeared to be an attempt to destabilise the Prime Minister.
The Salford MP was a former chairwoman of the Labour Party and one of the most prominent Blairites in Mr Brown's cabinet, but had come under pressure over her failure to pay capital gains tax on a property on which she claimed parliamentary second homes allowances. She repaid £13,000, but her action was branded "totally unacceptable" by the PM.
Downing Street said that Mr Brown "respects and understands" Ms Blears' decision to quit and would replace her "very shortly".
Opposition MPs leapt on her departure as an indication that the Government was in "meltdown" following weeks of bad publicity and tumbling opinion poll ratings.
Shadow cabinet member Theresa May told Sky News: "We have a Government that is in complete meltdown. I think the game is up for Gordon Brown. We are seeing a Government that is in its last dying throes."
Ms Blears told Mr Brown of her decision to quit at a face-to-face meeting, said Downing Street.
Mr Brown's spokesman said: "In the Prime Minister's view she has made an outstanding contribution to public life, most recently as Secretary of State for Communities and Local Government. He respects and understands the decision she has taken."
