Justice secretary Jack Straw has ruled out another Labour leader being made prime minister without a general election, calling it "unconstitutional".
Questioned on whether it was possible the prime minister would be replaced for a second time in a television interview yesterday, Mr Straw said: "Technically it would be unconstitutional, but it's not going to happen."
But when pushed on the question Mr Straw continued: "Refer to better constitutional theorists and historians for the answer to that."
The statement is being interpreted as a warning to any rebellious Labour party members conspiring to replace Mr Brown before the next general election - pencilled in for some time in 2010.
He then proceeded to stamp on any suggestion of challenges over the leadership.
"We have a leader," he said.
"He is the best leader we could possibly have and he will see us through these difficulties."
Mr Brown is widely expected to suffer his first parliamentary defeat over his proposal for 42-day pre-charge detention next week.