David Cameron could lose one of his prized four female Cabinet ministers if MPs condemn culture secretary Maria Miller over her expenses claims.
Backbenchers on the Commons' standards and privileges committee are reportedly split over Miller's mortgage claims on her second home, which her parents lived in.
The MPs are considering a report from parliamentary standards commissioner assessing whether Miller should have made the claims, totalling over £90,000.
Former New Labour minister Tony McNulty was forced to quit the government after he claimed a second homes allowance for a property his parents lived in.
Now parliamentarians are arguing over whether Miller would have to pay the same price.
Sir Alistair Graham, the former chairman of the committee on standards in public life, said: "Clearly a recommendation has been made by the Parliamentary Commissioner and they have a duty to consider it very seriously.
Sir Alistair Graham, the former chairman of the committee on standards in public life, said those at the top of government have to be "whiter than white" if they are to continue in their job.
"My view is that Cabinet ministers are in a special category and are expected to show leadership," he told the Telegraph newspaper.
"The MPs on the committee should be putting party political differences aside. If they look to be letting off one of their own class rather than taking a tough line that will be very damaging for democracy as a whole."
Miller has insisted her expenses claims have always been "absolutely in order".
She said: "For a considerable time before I entered politics, my parents have lived with me, my husband and our children as part of the family. I have always been open about these arrangements."
The mortgage for her second home, paid for by the taxpayer, was made the subject of scrutiny following a complaint by Labour MP John Mann.
But Miller seems to have been most frustrated with national newspapers' scrutiny of her allowances. Her aides have openly suggested to journalists she believes the attention is related to her role in the reform of newspapers' regulation.
Criticism of the standards and privileges committee was at the heart of reformers' case for introducing a recall mechanism that would have allowed voters to trigger a by-election.
The three main parties committed to the idea in their 2010 general election manifestos but the coalition produced a watered-down version which was rubbished by critics.
Writing on ConservativeHome, Tory MP Zac Goldsmith argued: "What was supposed to be a tool to enable voters to hold the institution to account has been transformed by Clegg into a tool for enabling the institution to hold itself to account.
"It is a breathtakingly cynical attempt to convey an impression of democratic reform without actually empowering voters in any sense at all."
News of ministers' decision to finally abandon that proposal emerged last week.