Jacqui Smith is to quit as Home Secretary
Another Cabinet casualty could be Chancellor Alistair Darling, whose career appeared to be hanging by a thread after he was forced to apologise for, and pay back, hundreds of pounds he wrongly claimed on his taxpayer-funded expenses.
He even had to revise the amount he repaid after quoting the wrong figure.
After telling broadcasters last night that he was repaying £350, an aide said today the true sum was nearly double that, at £668.
Transport Secretary Geoff Hoon was also under pressure after being forced to issue an apology and pay back money after admitting he had "accidentally" overclaimed £384.
Ms Hughes increased the sense of disarray in Westminster by telling the Prime Minister she wanted to leave the Government in his next reshuffle, which she suggested could be "very soon".
Ms Hughes will also be leaving Parliament at the next election, as will former health secretary Patricia Hewitt, it emerged today. Both cited family reasons and denied their decisions were related to the expenses scandal.
But they were the latest of 15 MPs who have lined up to hand in their resignation notices since the furore erupted almost four weeks ago.
Another Labour backbencher, Jim Devine, was facing de-selection today after being referred to the party's star chamber over allegations that he submitted receipts from a firm that may not have existed.
Gordon Brown, struggling to contain the expenses row, is to start chairing a new National Democratic Renewal Council, made up of ministers, from next week.
Asked today for his views about Mr Darling and Mr Hoon, Mr Brown's spokesman said: "He thinks they are both doing very good jobs."
Announcing his decision to go, Mr Chaytor said that, for the coming months, his "priority must be to explain my errors following allegations over the use of parliamentary allowances".
"This will be time-consuming and stressful," he went on, adding that he would not have time for constituency campaigning.
He is to repay nearly £13,000 he claimed by continuing to submit £1,175 monthly bills for mortgage interest months after the loan was paid off.
