Britain’s coalition govt. very likely to end before general election

"I think it would be logical and sensible for both parties to be able to present their separate vision to the public in time for the public to form a clear view before the election”, said Graham Brady, the chairman of the Tory 1922 committee.

"Of course, it is always possible that that moment of separation could come sooner. It's very difficult to predict when that might be," he added.

In a Sunday Times article, Prime Minister David Cameron, himself a Conservative, said it "would be insulting the public's intelligence to pretend there aren't profound areas of disagreement" between the Conservatives and the Liberal Democrats, citing Lords reform and Europe in particular.

But former Lib Dem leader Sir Menzies Campbell stirred the controversy by confirming rumours circulating in Westminster for weeks that many of his party's MPs would not be willing to vote through proposed changes to Commons constituency boundaries if the Lords bill was not passed, saying it would be "very hard to swallow".

Tory MP Stewart Jackson used Twitter to make his point on boundary changes more bluntly. "Memo to bolshy Lib Dems," he wrote. "Break deal on boundary changes and you'll be out of government the next day and maybe for ever. That vote has consequences too."

The former Tory defence secretary Liam Fox also risked stoking bad feeling by stating that the Lib Dems were only "a sixth" of the coalition and urging Cameron to be more "driven" in pushing Conservative policies, even when they are opposed by the Lib Dem leader Nick Clegg and his party.

Nadhim Zahawi, a usually loyal Tory backbencher who helped lead last week's Lords rebellion by 91 Conservative MPs, also appeared to turn up pressure on the party leadership, suggesting that unless a compromise could be made in "a couple of weeks", the reform proposals should be abandoned.