The buyout firm said in a statement that it had no wish to increase its 150p a share offer - the deal it touted after cutting its original 175p offer from January 2008.
Predictions of the takeover attempt's imminent collapse have already driven down stocks in Friends by around ten per cent.
The firm's comments also contained an explicit threat that the deal would soon be cancelled.
"In the event that the board of Friends Provident does not enter into discussions with JC Flowers prior to the close of business on Friday ... it is JC Flowers' intention to formally withdraw its proposal," the statement continued.
Speaking to the newspaper, anonymous sources "close" to Flowers still expressed hope that the deal would go ahead, however.
"The question is: do you want 150p in cash now, or will you take a bet on a recovery story that might happen in a couple of months or might not happen at all," one source commented.