Vince Cable knew about Matthew Oakeshott's polling, the peer has revealed, as he quits Westminster with a defiant call for Nick Clegg to resign.
Oakeshott, who has issued a statement making clear the party is "heading for disaster if it keeps Nick Clegg", will have damaged his long-time ally Cable in the final act of his political career with the revelation.
It follows the leak of privately commissioned polling data from Oakeshott's office revealing that the Lib Dems were on track to lose four seats - including Clegg's own Sheffield Hallam.
Oakeshott revealed he had commissioned polling in a fifth seat - Treasury chief secretary Danny Alexander's Inverness, Nairn, Badenoch and Strathspey - which it later emerged reveals the SNP are set to take the constituency. They lead by 32% to Alexander's 16%.
He also suggested political parties were continuing to accept cash in return for awarding peerages, a criminal offence.
Cable was forced to issue two statements in as many days reaffirming his support for Clegg, who spent the morning attempting to recover from last week's European elections wipeout with a well-received speech on international development.
Now Oakeshott, 67, has derailed coverage of Clegg's speech by dramatically resigning his membership of the Liberal Democrats and taking a leave of absence from the Lords "to concentrate on running my business and my charity".
"I leave, with a heavy heart, the party I helped to found with such high hopes with Roy Jenkins, Bill Rodgers, Shirley Williams and David Owen at Limehouse in 1981," he said in the statement.
"We then, like most Liberal Democrats now, wanted a radical progressive party, not a 'split the difference' Centre Party, with, in Shirley’s memorable words, no roots, no principles and no values. But that is where Nick Clegg has led us."
Oakeshott has been the most consistently vocal opponent of Clegg's leadership for many years - but has now been comprehensively outmanoeuvred.
He said he had commissioned polling from ICM on the suggestion of an unnamed "close colleague" who was "concerned about voting intentions in Twickenham", Cable's constituency.
The polling was amended and approved by Cable, although the business secretary requested that the questions about the alternative leader be removed, Oakeshott explained. The data showed Cable was behind the local Conservatives.
He added: "That poll worried me so much that I commissioned four more in different types of constituency all over the country and added back the change of leadership question... several weeks ago, I told Vince the results of those four polls too."
Question-marks have emerged over the accuracy of the polls' methodology, however. Some of those questioned were asked to consider whether they would vote for Ukip as well as other parties, while candidates' names were not included - thus negating the incumbency factor typically enjoyed by Lib Dems.
"We believe that a candidate named, regular methodology poll from ICM would show Cambridge and Sheffield Hallam as clear Lib Dem holds," Damien Lyons Lowe and Katy Owen of Survation wrote.
"Tessa Munt is not 20 points adrift in Wells and that Redcar is a likely Labour gain on paper should be a surprise to no-one."
A Liberal Democrat spokesperson said Oakeshott's decision was "understandable in the circumstances".
"These have been a difficult few days after a disappointing set of election results," the statement said.
"But now is the time to get on with the business of government and getting our message out about what the Liberal Democrats are delivering in government to build a stronger economy and a fairer society – cutting income tax, bringing down the deficit, creating jobs and making sure everyone benefits from our economic recovery.”