Fears of an embarrassing gap in the financial plans of the Royal Institution are casting doubts over the future of its director, Baroness Susan Greenfield.
Members of the governing council believe Lady Greenfield will be forced to resign if the institution fails to raise matching funds for a Heritage Lottery Fund grant of almost £5 million.
Concern is growing among senior council figures that the organisation may have to pull out of the most ambitious building project in its 200-year history because sufficient funding has not been secured.
The HLF said it would be highly unusual for an organisation not to generate partnership funds - and lose out on a grant.
Lady Greenfield won a grant of almost £5 million for the institution to build a new museum, cafe and bar on the understanding that the institution would raise its own matching funds by the beginning of next year.
Lady Greenfield said there was no reason to think that money was not forthcoming. But council members have said they have received no evidence that matching money has been secured.
One council member, who asked to remain anonymous, said: "Those of us who have tried to raise money know a large amount of money like this takes a long time to get in the bag. Time is running out."
The source said that if all of the required funding - believed to be about £5 million - had not been secured by the end of the year, the majority of council members would decide that the high-profile project could not go ahead.
The source added: "Then she (Lady Greenfield) would have to leave of her own accord. She certainly should. Her position would be untenable."
According to council members, there has been talk of donations on the horizon, including a recent possibility of a legacy, but no firm offer has been made. Building work has not begun, although the RI has invested a substantial sum of money in planning stages.
Another council member told The Times Higher : "There is a worry about the relatively short timescale in which to raise the money." The member said it was unlikely lottery funding would be released without matched funds.
The HLF said this week that it liaised carefully with all its applicants, but it had not been alerted to any problems by the RI. A spokesperson said the HLF was "hugely supportive" of the project.
But she said: "They are at stage one (of the funding process) at the moment and can't go forward to stage two unless they have partnership funding in place."
Henry "Val" Tyrell, who was chair of the RI's buildings working party when the project was first discussed but who has now retired, said: "I was concerned and not very enthusiastic as I thought the funding would be out of scale."
He added: "The new director was extremely enthusiastic. It was her great idea, therefore plans were laid. One or two of us tried to talk her out of it, but we didn't succeed."
Lady Greenfield and Winston Fletcher, chairman of the RI council, said in a statement: "Like any other organisation involved in a fundraising campaign, the RI is unwilling to provide detailed information in the middle of the process. Since receiving our first tranche of HLF funding earlier this year, we have been in close contact with numerous major charitable and individual funders: we now have every reason to believe we will reach the sum required to gain the remaining HLF funding by the due date."
Since becoming the first female director of the RI in 1998, Lady Greenfield has won praise for her efforts to encourage the public to take an interest in science.