British Prime Minister David Cameron will on Monday defend his decision to veto a new European Union treaty after the move triggered fury among his Liberal Democrat coalition partners.
Amid the most serious crisis yet faced by the coalition, Cameron will tell lawmakers that Britain had to wield its veto at Friday's EU summit in Brussels in order to protect its crucial financial services sector.
He will likely receive a hero's welcome from eurosceptic lawmakers in his Conservative party during the House of Commons statement, delighted their leader has shown "bulldog spirit".
But the reaction from his junior coalition partners, the pro-Europe Liberal Democrats, will be far more hostile after tensions escalated dramatically at the weekend.
Deputy Prime Minister Nick Clegg, the Lib Dem leader, on Sunday vented the anger felt by many in his party when he warned Cameron the veto risked leaving Britain "isolated and marginalised" in the EU.
After initially backing the veto, former European lawmaker Clegg broke ranks and launched a scathing attack on his Tory boss, saying the move could diminish Britain's standing on the world stage.
"I think a Britain which leaves the EU will be considered to be irrelevant by Washington and will be considered a pygmy in the world," he said.
Britain opted out of an agreement by the other 26 EU states to join a "new fiscal compact" aimed at saving the euro at an all-night summit in Brussels, angering much of Europe as it tries to prop up the single currency.
The coalition is now facing its biggest threat since its formation after an inconclusive general election in May last year, although leaders from both sides insisted it was not on the verge of collapse.
Foreign Secretary William Hague, a former Conservative party leader and noted eurosceptic, hit back at Clegg, insisting that Britain had not lost influence by blocking the treaty.
"It does not leave us isolated or marginalised in Europe because we continue every day to work with our European partners on a vast range of subjects," he told BBC radio.
He added the Tories and Lib Dems "will continue to work together" but his diplomatic language could not mask an increasingly bitter war of words in the rank-and-file of the parties.
Lib Dem lawmaker Jenny Tonge suggested her party's patience with the coalition was coming to an end.
"We've had one thing after another come at us as a party and I think at some stage we've got to say enough is enough, either we say 'stop this nonsense and the coalition cannot go on', or the Conservatives decide to change tack," she told BBC radio.
Former Lib Dem leader Paddy Ashdown said the veto was a "catastrophically bad move" but Mark Pritchard, a leading Conservative eurosceptic, hit back.
"People are getting rather fed up of the self-righteous whinging of some Lib Dems who are totally out of step with public and mainstream euroscepticism and have called it wrong on Europe for years," he said.
The veto has encouraged a hardcore of Conservative lawmakers to push for a referendum on Britain's troubled membership with the EU.
Britain's rightwing press, which heaped praise on Cameron over the weekend for blocking the treaty, took aim at Clegg on Monday for criticising the veto.
"Villain Clegg," said the Rupert Murdoch-owned Sun newspaper, Britain's biggest selling daily.
"He is a cynical opportunist willing to leave no principal unturned for short-term political advantage."
Despite the political storm the veto has unleashed, a new poll Monday showed strong public support for the move. Fifty-seven percent of people quizzed for a Times survey backed the veto while only 14 percent disagreed.
It was the second poll to show strong support for Cameron's actions.
In Scotland, First Minister Alex Salmond criticised the veto, accusing Cameron of putting Scottish interests at risk without first having consulted the devolved administration in Edinburgh.