The condemnation of Lib Dem peer Lord Oakeshott, who was accused of commissioning a poll which suggested the party would fare better with the Business Secretary at the helm, came as Ed Miliband made clear he would never bow to pressure from Ukip to take Britain out of the European Union because "our future lies in looking outward to the world".
After a crestfallen Mr Clegg insisted he would not resign following the loss of all but one of his party's 12 MEPs, it was claimed an internal poll, suggesting the leader could lose his Sheffield seat at the next election, had been commissioned by his arch critic Lord Oakeshott, who subsequently leaked it, seemingly to cause the Deputy Prime Minister maximum damage.
The peer has consistently championed Mr Cable but when the Secretary of State learned of how the poll had supposedly come about, he fired off a blistering put-down. "Lord Oakeshott's actions are totally inexcusable and unacceptable. I have made it very clear repeatedly that he does not speak or act for me," declared Mr Cable.
"Commissioning and publishing polls without the consent of the Member of Parliament, as in the case of Sheffield Hallam, is utterly reprehensible. There are undoubtedly raw feelings in the wake of poor local and European election results. We need to respond in a measured way.
"Public speculation about the leadership is an unwelcome distraction and as I made absolutely clear yesterday there is no leadership issue as far as I'm concerned," he added.
Earlier, a poll of almost 1,000 party members for LibDemVoice.org showed 54 per cent wanted Mr Clegg to stay as leader with 39 per cent saying he should step aside. But while 51 per cent said they were satisfied by the DPM's performance, 48 per cent said they were not. Meantime, Mr Miliband took to the campaign trail in Essex, where Ukip did well in last week's local elections.
He admitted Nigel Farage's party had sought to exploit the feeling among many people that Labour's role of standing up for working people had been lost.
"We know what their appeal is; they provide a simple explanation of the cause of our country's problems: Europe and foreigners. And they have an apparently simple solution: to get out of the European Union. I have to say: this is not the answer for our country, this will never be Labour's mission or policy under my leadership. Our future lies in looking outward to the world," insisted the Labour leader.
He made clear it was not prejudiced to worry about immigration but understandable.
Labour would have controls when people arrived and left the UK, it would tackle the undercutting of wages, ensure people in public services spoke English and had to earn entitlements.
"But," Mr Miliband added, "a Labour government won't make false promises or cut ourselves off from the rest of the world because it would be bad for Britain."