The financier Michael Brown, the Liberal Democrats' controversial backer, has withdrawn his financial support after dubbing the party "muppets".
In a statement released exclusively to The Independent on Sunday, Mr Brown, who last year gave the party £2.4m to fight the general election, also defended its former leader Charles Kennedy.
"Following my recent £2.4m donation," he said, "it was my intention to provide the Liberal Democrats with further support and loan finance - until the party unceremoniously sacked Charles Kennedy as its leader, which did not augur well for the future or represent a good return on my investment."
He continued: "The muppets in the Liberal Democrats who purported to serve Charles Kennedy decided to kick their leader when he was down - something that the electorate will not easily forgive or forget. I was outraged by this behaviour."
He also made a veiled attack on the party's new leader, Sir Menzies Campbell. "The speed with which I was persuaded to support the Liberal Democrats could have been repeated by many other business colleagues, leading entrepreneurs, associates and friends. I am not going to be judgemental, but others will form their own view whether it is a good idea to ever support the Liberal Democrats, and whether under the current leadership they will ever be able to form a government."
The £2.4m gift from the Scottish financier, who is based in Majorca, prompted a probe by the Electoral Commission which eventually concluded that it did not break any rules. But it later emerged that Mr Brown was being sued by his bank, HSBC, and faces having his assets frozen, as well as being wanted for alleged fraud in the US.
Mr Brown said he "never requested or expected" a peerage for his support, adding that the party did not contact him at any time during its leadership race.
The Liberal Democrats declined to comment.