David Cameron is warning the Liberal Democrat leadership that he "doesn't expect any nonsense" over plans to radically redraw Britain's electoral map which could result in the party losing up to 15 of its 57 MPs.
Liberal Democrat officials say they are facing growing "disquiet and discontent" from party MPs who may lose their jobs as part of plans to reduce the number of seats in the House of Commons from 650 to 600.
But last night No 10 made it clear that Mr Cameron expected Nick Clegg to ensure his MPs backed the changes which were included in the Coalition agreement in return for the referendum on the alternative vote (AV).
"We gave them their referendum and now we expect them to deliver on their side of the deal," said a senior government source. "We do not expect any nonsense from them on this."
But Downing Street is aware that there could be a backlash from Tory MPs, who may lose their seats as a result of proposed boundary changes.
Yesterday, Eric Pickles, the Communities Secretary, suggested some of the proposals were flawed and might have to be revised.
Richard Graham, Tory MP for Gloucester, who faces losing the city centre from his constituency, said he would fight the changes "tooth and nail".
Gary Streeter, the Conservative MP for South West Devon, whose seat will disappear, added: "To me these proposals... look like a dog's dinner."
What will worry the Conservative leadership is the emergence of a "rebel coalition" of dissatisfied Tory and Liberal Democrat MPs who could join with Labour to defeat the changes.
The changes, proposed by the Boundary Commission, will now be subject to a 12-week consultation period after which it will present its final plan. However, if the proposals are defeated in Parliament, the reduction in seat numbers will be delayed and the 2015 election will be fought using the 2010 boundaries.
Among MPs who could suffer is Vince Cable. His Twickenham seat is being carved up to create a new Richmond and Twickenham constituency.
"In order to get the right size of constituency, no account has been taken not just of borough boundaries, but any sense of identity," he said.
He believes that the Liberal Democrats could emerge as "double losers" on constitutional reform, having already lost the AV referendum and now at risk of getting fewer seats.Reuse content