Oakeshott quits Lib Dems with Clegg 'disaster' warning
Lord Oakeshott has quit the Lib Dems with a warning the party is "heading for disaster" under Nick Clegg.
The peer, a former Treasury spokesman for the party who is seen as close to Vince Cable, said the party had lost its "roots, principles and values".
He quit after it emerged he commissioned polls suggesting the party would do better without Mr Clegg.
Mr Cable has denounced his actions but the peer said the business secretary knew about the poll and its findings.
Mr Cable, who is currently in China on government business, said he knew Lord Oakeshott was paying for private opinion polls in Mr Cable's Twickenham constituency and some other areas as part of the party's general election planning.
But he had "absolutely no knowledge" of polls being carried out in Mr Clegg's Sheffield Hallam constituency or the Inverness constituency of Treasury minister Danny Alexander.
"I criticised them [the polls] very seriously yesterday but I am here to do a job of work promoting British exports and jobs and that is what I intend to get on with," he said.
He described Lord Oakeshott as a "longstanding friend" and said he regretted "we've finished up in this way," adding he hoped the peer would reconsider his resignation from the party.
Mr Clegg has accused Lord Oakeshott of seeking to "undermine" the Lib Dems, and senior party sources have told the BBC the peer had been "disowned" after a "shambolic attempt at a coup" and for "pursuing his own malicious agenda".
The row comes after the Lib Dems' dire performance in European elections.
Mr Clegg has faced calls to step down from 300 activists while a number of constituency associations, including Liverpool and Cambridge, are to hold meetings to discuss their leader's future.
In a statement, Lord Oakeshott said he was leaving the party "with a heavy heart" and issued a warning to the Lib Dems about their future prospects.
"I am sure the party is heading for disaster if it keeps Nick Clegg; and I must not get in the way of the many brave Liberal Democrats fighting for change," he said.
He suggested that under Mr Clegg's leadership the Lib Dems had become a "split-the-difference centre party, with no roots, no principles and no values" rather than a "radical, progressive party".
He said the message behind Mr Clegg's "dire approval ratings year after year in all national polls, and Thursday's appalling council and European election results, is crystal-clear.
"We must change the leader to give Liberal Democrat MPs their best chance to win in 2015."
He added: "I am sorry I have so upset and embarrassed my old friend Vince Cable and that we were not able to talk before he issued yesterday's statement from China."
By Iain Watson, Political correspondent
Lord Oakeshott 's parting shot as he quit the Lib Dems may have been aimed at the leader he thinks will lead the party to oblivion… but it also ricocheted off Vince Cable. Lord Oakeshott was denounced by the Lib Dem leadership for spending money on polls that could have been spent on campaigning. But he suggests in his statement that Vince Cable knew all about them: "Several weeks ago, I told Vince the results of those four polls." Even if it was Lord Oakeshott's decision alone to commission the polling, it makes Mr Cable's condemnation of these actions yesterday - when he called them "reprehensible" - look politically convenient and perhaps a little unconvincing. He will be facing a barrage of questions on his return from the Far East - if not sooner.
Mr Clegg had said earlier on Wednesday said it was "wholly unacceptable" that a senior member of the party "rather than trying to go out and win votes was spending money and time trying to undermine the fortunes of the party".
The Lib Dems have said they are "100% sure" that Mr Cable played no part in the poll and that the business secretary took "proactive steps" to denounce it.
In his statement, Lord Oakeshott suggested that he had told Mr Cable about the poll findings "several weeks ago" before the outcome of European elections and before they were leaked to the media on Tuesday.
Former Lib Dem leader Sir Menzies Campbell said the peer's position had become "quite untenable" when it emerged he had commissioned the polls "in secret" and "allegedly leaked them to the media".
Sir Menzies also suggested the peer had plotted against him when he was leader.
"Lord Oakeshott has conceived of himself as something of a kingmaker and has gone beyond his competencies in the matter," he told Radio 4's World at One.
Justice Minister Simon Hughes, the party's former deputy leader, accused Lord Oakeshott of "utterly reprehensible" behaviour and of acting in a way that was against the interests of the party.
It emerged on Tuesday that Lord Oakeshott had paid for an ICM poll that suggested the Lib Dems would pick up votes in four seats, including Mr Clegg's own Sheffield Hallam constituency, if Mr Cable or other figures replaced Mr Clegg as leader.
It suggested that the party was on course to lose Sheffield Hallam and three other seats - Cambridge, Redcar and Wells - next year unless there was a change at the top.
The polls, conducted without Mr Clegg's knowledge, were taken in April and early May.
Although the polls suggested there would be a rise in support for the Lib Dems if a number of alternative figures replaced Mr Clegg, it suggested the party could still struggle to retain any of the seats.
Lord Oakeshott has subsequently published polls suggesting the Lib Dems are vulnerable in Mr Cable's own seat, Twickenham, and the Inverness constituency of Mr Alexander.
Who is Lord Oakeshott?
Matthew Oakeshott, 67, began his career in politics in the 1970s as a Labour councillor and then a special adviser to Labour Home Secretary Roy Jenkins. He joined Jenkins in the breakaway SDP in the early 1980s, when he stood unsuccessfully as an SDP Liberal Alliance candidate. He went on to make a fortune in the City as a property investor and investment manager. In 2000, he was made a life peer and spent 10 years as Lib Dem treasury spokesman in the Lords. He was forced to quit that role in 2011 over his criticism of the Project Merlin deal between the banks and the government. An old friend and ally of Vince Cable, Lord Oakeshott has long been seen as the business secretary's unofficial spokesman. But his strident criticism of coalition policy and calls for Mr Cable to replace Nick Clegg as Lib Dem leader have led to a cooling of their relationship, in public at least.
On Tuesday Mr Cable described Lord Oakeshott's actions as "totally inexcusable and unacceptable".
"Commissioning and publishing polls without the consent of the Member of Parliament, as in the case of Sheffield Hallam, is utterly reprehensible," he said .
"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."
A separate poll by the Liberal Democrat Voice website on Tuesday suggested 39% of party supporters wanted Mr Clegg to step down, with 54% backing him.