David Cameron faces being left looking more pro-Europe than both his own MPs and Labour after the opposition attempted to outflank him by demanding a cut in the EU's budget.
The prime minister is trying to prevent the 5% rise requested by the European Commission - but has accepted that it should rise in line with inflation, or around 2%.
However writing in The Times today, shadow foreign secretary Douglas Alexander and shadow chancellor Ed Balls said there should instead be a "real-terms cut in the budget".
“Every country across Europe, including Britain, is having to make difficult decisions about spending, trying to do better with less," they said. "And the European Union is not — and should not be — exempt from this challenge.
"Our fear is that the prime minister is throwing away an opportunity to deliver a budget that is best for Britain and right for the EU.”
The article is the second attempt by the party to encircle Cameron on the EU - a press release issued on Tuesday by the party called for a real terms Budget cut was largely ignored by the media.
On Wednesday MPs will be asked to approve aspects of the EU Budget. But backbench Tory Mark Reckless intends to table an amendment that will urge MPs to vote to block any real-terms increase - a move that will unite a large swathe of Tory MPs with Labour against the government.
Writing on his blog today Reckless said: "Some real terms reduction is surely not an unachievable or excessively radical goal, given the extent to which we and other EU countries are making less palatable cuts at home."
On the same day Stewart Jackson, the Tory MP for Peterborough, will introduce a Bill calling for the UK to crack down in immigrants from the EU - a hot button issue for many Tories.
Reckless and Stewart will hope the topic of the EU will dominate the day as Cameron faces a grilling from Ed Mliband at prime minister's questions.
Foreign secretary William Hague is also likely to be quizzed over the EU budget negotiations when he faces MPs in the Commons on Tuesday afternoon.
Also beating the eurosceptic drum this morning for Labour was Gisela Stuart. Appearing on BBC Radio 4's Analysis programme, the Birmingham MP was asked if Britain should leave the EU. "I think ultimately it has to go that way, yes," she said.
It has been suggested that Labour may attempt to further outflank the Tories on Europe by coming out in favour of a referendum on Britain's membership. Marcus Roberts, the deputy general secretary of the Fabian Society warned Conservative MPs last month that Labour could be "ruthless" on the issue and would promise a public vote if the prime minister refused to do so.
On Friday MPs debated a Bill pushed by Tory MP Doublas Carswell that would take Britain out of the European Union.
And Labour shadow foreign minister John Spellar reserved his criticism of the Bill to simply noting that it did "not consult the people" as it would leave the decision to exit the EU to MPs rather than voters.
However a more eurosceptic tone from Labour is not without risk for Ed Milband. Responding to Gisela Stuart, former Labour europe minister Peter Hain said she was "fundamentally wrong".
"Leaving the European Union but then seeking access to its single market as we would have to do – half Britain’s trade is with the EU – would leave us having to comply with all the rules of the single market without having a vote on them as we do now, and it would cost us more than we pay into the EU now. Hardly commonsense a better deal," he told The Huffington Post UK.