Defiant MPs are steeling themselves for one last effort to salvage some family perks from the wreckage of the parliamentary expenses scandal.

Proposed reforms being announced this morning include measures designed to eradicate taxpayer-funded mortgages on second homes and their right to employ relatives. Some MPs have condemned these as draconian.

The recommendations from Sir Christopher Kelly’s Committee on Standards in Public Life were endorsed in principle by the Cabinet yesterday. David Cameron has made plain to his MPs that they should back the reforms — and preferably keep their concerns to themselves.

Last night the Speaker’s committee agreed to offer the job of chairman of the new Independent Parliamentary Standards Authority (IPSA) to Professor Sir Ian Kennedy and, if he accepts, it will be announced officially today.

Downing Street and the Tory leadership, however, acknowledge that Parliament’s expenses watchdog will come under intense pressure to make “reasonable adjustments” before new rules are finally agreed in February or March next year.

The Times has learnt that a number of MPs, including some senior frontbenchers, will tell the IPSA that politicians’ families will be the innocent victims of reform.

Caroline Spelman, the Shadow Communities Secretary, is understood to be particularly “sympathetic” over the plight of women Tory parliamentary candidates with young children.

While the Kelly report has given existing MPs five years’ grace to move from mortgaged homes into rented accommodation, the new intake after the next election are expected to have no such option.

A Tory source said it was wrong to expect new MPs and the families to atone for the behaviour of what has become known as the “manure Parliament”.

Under the Kelly reforms MPs will likely be given a tight rental budget or placed in “billets” allocated and managed by the IPSA. A Tory MP suggested yesterday that these might be one-bedroom flats in poorer London boroughs far from Westminster.

MPs will use a consultation period of up to eight weeks to make their cases to the IPSA that special circumstances justify weakening or delaying key reforms.

“Work will have to be done on the implementation with practical issues involving family circumstances,” a government official said. “But that should not be used as a means for trashing the whole report. The Prime Minister is determined that it should be agreed in full before the election.”

Several MPs are believed to be arguing that the sale of second homes or the sacking of family members employed as staff should be phased in over a much longer period of 10, or even, 15 years. Yesterday one frontbench Conservative spokesman talked of exploiting “wiggle room” in the report.

Harriet Harman, the Leader of the Commons, who will make a statement to the House today, has already hinted that the IPSA may conclude that it would be unfair to make MPs sack spouses and other family members.

A number of MPs, including those who bought at the top of the property market after being elected in 2005, will point out that their homes have fallen in value and they have negative equity. They fear big losses if they have to sell before the market recovers.

Others are angry over a proposal in the Kelly report that will prevent MPs whose constituencies are an hour’s journey from Parliament from having any funding at all for second homes. Some are preparing to argue that their door-to-door journey is much longer and “impractical when there is a late-night vote”. One MP, who has been told that the “60-minute rule is likely to be imposed immediately after the election” has already put a family home in the commuterbelt up for sale.

The Kelly report is also expected to call for a cut in the travel budget, which allows spouses and children the right to first-class train tickets.

Although party leaders are urging MPs to keep quiet today for fear of alienating voters even further, criticism is expected to be fiercest today from some of those who have already decided to quit politics. Sir Nicholas Winterton, the Tory MP for Macclesfield, said that “the way MPs are being treated is quite despicable”.

He added: “Mr Kelly is a senior civil servant on a generous index pension link who is trying to reduce MPs to abject poverty and I don’t know why.”

Anthony Steen, the Tory MP for Totnes, who announced his retirement after being criticised for comparing his home to Balmoral, insisted that he had behaved “impeccably”. He added: “Do you know what it is about? Jealousy. I have got a very, very large house. We lost our empire and now we are losing our Parliament. There is an unjustness to a system that is being accepted by the powers.”

Additional reporting: Tim Glanfield; Sakshi Ojha; Samantha Hockney; Sanne Rooseboom; Sean McCaffrey

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