MPs may mutiny over changes to constituencies.
George Osborne's Tatton seat is among those that could disappear in the boundary change.
David Cameron and Nick Clegg are braced for a collapse in coalition discipline when dozens of MPs learn this week that their constituencies are to be axed.
The redrawing of parliamentary boundaries, which will cut the number of MPs from 650 to 600, will ignite a political storm tomorrow, with government whips fearing that the prospect of being kicked out of the Commons could lead some MPs into rebellion for the next three years.
"Trying to control Lib Dems is like herding cats at the best of times," said one party source. "If a dozen are de-mob happy, counting down till polling day when they know they'll be out on their ear, it will be a nightmare."
Senior ministers including George Osborne, the Chancellor, Grant Shapps, the Housing Minister, and Danny Alexander, the Chief Secretary to the Treasury, are among those whose seats are under threat.
It raises the prospect of more junior MPs being shunted out of safe seats to make way for key government figures. "It will be every man and woman for themselves," a Tory backbencher said. "It will be piranha pool-time," said another. There is even speculation that some disgruntled MPs could quit within weeks, sparking a wave of by-elections.
MPs will be briefed on the plans tomorrow, before they are published officially by the Boundary Commission on Tuesday. They will only cover England, with Scotland, Wales and Northern Ireland following later this year. In England there will be 502 new seats. Two will be on the Isle of Wight, but the remaining 500 will have to have between 80,473 and 72,810 voters. There have already been rows about planned constituencies spanning county borders, with Devon and Cornwall MPs refusing to countenance the idea of straddling the Tamar.
In Leeds a tussle is being predicted between Ed Balls, Labour's Shadow Chancellor, and Hilary Benn, the Shadow Leader of the House, while in north-west Scotland, Mr Alexander could be pitched against former Lib Dem leader Charles Kennedy for a berth.
Analysis by Rob Haywood, a former Tory MP, suggests that Labour stands to lose 25 seats, the Tories 15 and Lib Dems 10, while Lewis Baston, a senior research fellow at the University of Liverpool, predicted that Labour would lose 18 seats, the Tories 15 and Lib Dems 14, with other parties losing three.
Labour has accused the coalition of gerrymandering, while No 10 insists the high number of seats with relatively small electorates favours the Labour Party. At the last election, the average Labour seat had an electorate of 68,487 compared to 72,418 in Tory-won constituencies and 69,440 for Lib Dems. Downing Street argues the policy will save £12m a year.
"By making constituencies more equal in size, the value of people's votes will no longer depend on where you live, and with fewer MPs the cost of politics will be cut," a source said.
A 12-week consultation will be followed by a second phase allowing parties to respond to each other's complaints.