Business Secretary Lord Mandelson has issued a warning to Labour rebels to "stop taking shots" at Gordon Brown.
As the party braced itself for another mauling when the European election results are announced tonight, Lord Mandelson said they would face "irresistible pressure" to hold a general election if they got rid of another leader.
"If we were to have a third leader in a single parliament it would mean irresistible pressure to hold a general election," he told BBC1's The Andrew Marr Show.
Lord Mandelson, who was effectively anointed as deputy prime minister in last week's Cabinet reshuffle, said that he did not know whether rebel Labour backbenchers were plotting to oust Mr Brown.
But he made clear that he did not believe that a coup attempt by the so-called "peasants revolt" would succeed.
"It would require somebody to stand against him, somebody who is raising their standard and saying that they could do a better job and we don't have that person," he said.
He acknowledged that the Government was going through a period of turbulence, but he insisted that it was still possible to turn the situation around.
"I am not saying that public opinion will turn on a sixpence but if we concentrate on what we believe in, our policies and what we are good at, then we will be able to turn public opinion," he said.
Asked about his message to would-be rebels, he said: "Stop taking shots at the Prime Minister because you are simply going to make the position of the party and the Government even worse."
