A third British minister resigned from Prime Minister Gordon Brown's government late Thursday and called on the leader to step down.
Work and Pensions Secretary James Purnell announced his resignation in a letter to Brown sent to several newspapers after polls had closed in European and local elections.
Purnell wrote that Brown should quit his position for the good of the Labour Party and that his leadership made a victory by the opposition Conservatives likely in the next election.
"I owe it to our Party to say what I believe no matter how hard that may be," Purnell wrote. "I now believe your continued leadership makes a Conservative victory more, not less likely."
He said Brown should "stand aside to give our Party a fighting chance of winning."
Brown was Thursday reported to be working on a fundamental re-shaping of his government which he hopes will ensure his own political survival and draw a line under the damaging scandal over parliamentary expenses.
As Britons were voting in European and local elections expected to be crucial to his political future, Brown was locked in discussions with advisers on how to move forward from the expenses scandal that has spiralled into a leadership crisis.
Two other ministers, Communities Secretary Hazel Blears and Home Secretary Jacqui Smith, had already resigned from the cabinet, with at least two more high-profile ministers expected to go.
Alistair Darling, the powerful Chancellor of the Exchequer, and Geoff Hoon, Transport Secretary, have admitted making "mistakes" in their expenses claims on property, and have paid back sums owed to the taxpayer.
Reports said Thursday that Darling had resisted attempts to move him to the Home Office portfolio, insisting that he wanted to stay in his job or not be part of the government at all.
Foreign Secretary David Miliband had also resisted moves to shift him to the Home Office.
The possible loss of Darling would be a body blow to Brown, commentators said Thursday. The two men have worked closely together for many years, and especially over the banking crisis and the anti-recession measures agreed in recent months.