Ruth Kelly reignited Labour tensions over Gordon Brown's future as she heaped praise on David Miliband and refused to rule out an attempt to oust the Prime Minister.
The departing Transport Secretary is believed to be one of several ministers whose patience with Mr Brown's leadership style has been wearing thin following two by-election disasters and a collapse in Labour's popularity.
Asked if there was a political element to her decision to step down, she told London's Evening Standard: "Yes, there was a balance, as there often is in life. But my prime concern was my family and a desire to see more of my children." Ms Kelly said she hoped Mr Brown would not use the cabinet reshuffle, expected next week, to remove or sideline Blairite ministers.
She also paid tribute to Mr Miliband, saying: "He is one of the great talents of the Cabinet – a star of the future, a real asset and a good friend."