British Prime Minister Gordon Brown has begun reshuffling his government in the face of a growing crisis.
Three senior ministers have left the government this week, with the latest, James Purnell, calling on Mr Brown to resign.
Mr Brown has had to move fast to reshuffle his cabinet after the surprise resignation of Mr Purnell.
Health Secretary Alan Johnson is to replace Jacqui Smith as Home Secretary. He is the man some Labour MPs want to take over from Mr Brown should he fall, the BBC reports.
Alistair Darling, the Chancellor of the Exchequer, is thought to be staying put at the Treasury.
No cabinet minister has followed Mr Purnell and called on Mr Brown to resign.
Mr Purnell's resignation came as the polls closed on Thursday for the European and English local elections.
In a letter published in several newspapers, the work and pensions secretary said he was not seeking the leadership but wrote: "I now believe your continued leadership makes a Conservative victory more, not less likely. That would be disastrous for our country."
It comes after the resignation of Ms Smith, Communities Secretary Hazel Blears and two junior ministers.
Labour is, meanwhile, waiting for more English local elections results to be declared - with the first few suggesting they could be among the party's worst.
The results of the European election, which was also held on Thursday, will start to be published from Sunday night.
Labour, which has been in power since 1997, is trailing far behind the opposition Conservatives in opinion polls.