As British Prime Minister David Cameron arrives in Washington to press for a new EU-US trade deal, prominent members of his cabinet said they would vote against the UK remaining part of the European Union (EU).
Usually-loyal government ministers Michael Gove and Philip Hammond, secretaries of education and defense respectively, announced on Sunday that both would vote to leave the EU if a referendum was held now.
Their opposition to the U.K.'s current position in the Union follows calls last week by two former Tory ministers, Lord Lawson and Michael Portillo, for Britain to finally revoke its EU membership.
Cameron – who has said he will hold an "in or out" referendum in 2017 if his party wins an overall majority at the 2015 election - has stated that he will support continued EU membership and said that his ministers supported his strategy of reforming the EU before holding an eventual referendum.
Cameron said, "What matters is making sure that we do everything we can to reform the EU...Every Conservative cabinet minister is confident that we'll be able to deliver those changes. We're all confident of the success."
The prime minister is currently in Washington hoping to push through a new EU-US trade deal that he says will bring 10 billion pounds in annual benefits to the U.K.
The EU debate has reared its head once again in the U.K. following local election results earlier this month in which the UK Independence Party (UKIP) – an anti-EU group – emerged as the main winners. UKIP won 147 local council seats, a sizable increase from the eight seats it won in 2009.
While Gove and Hammond are opposed to Britain's current position within the EU, both stressed that if the U.K. was successful in reforming aspects of its Union membership they would alter their stance in any subsequent referendum.
Gove told the BBC on Sunday: "My ideal is exactly what the majority of the British public's ideal is, which is to recognize the current situation is no good, to say that life outside would be perfectly tolerable, we could contemplate it, there would be certain advantages."
"But the best deal for Europe, and for Britain, would be if Britain were to lead the change that Europe needs," he said.
However, Lord Lawson's opposition to EU membership was unequivocal, arguing that there were clear positive economic advantages to the U.K. leaving the single market.
Lawson, who served as finance minister under Margaret Thatcher, said an exit from the EU - which he described as a "bureaucratic monstrosity" - would help businesses that have become too content with EU benefits.
"Over the past decade UK exports to the EU have risen in cash terms by some 40 percent. Over the same period, exports to the EU from those outside it have risen by 75 percent," he said.
London's Major Boris Johnson also argued that Britain must be prepared to walk away from the EU if sufficient reforms were not secured, but added that the UK should recognize that a lot of its problems were not, in fact, caused by the EU.
"Why are we still, person for person, so much less productive than the Germans? That is now a question more than a century old, and the answer is nothing to do with the EU. In or out of the EU, we must have a clear vision of how we are going to be competitive in a global economy," he wrote in The Sunday Telegraph.
(Read More: Nearly 20% of UK Businesses Favor EU Withdrawal)
His comments came after some Tory MPs expressed disappointment that Cameron did not include legislation in the Queen's Speech last week that would ensure a referendum took place.
A number of MPs have tabled an amendment to include this legislation in the Speech, which was supported by London's mayor, Boris Johnson, this weekend.
If there is a House of Commons vote on an amendment to the Queen's Speech calling for referendum legislation, government ministers have been advised to abstain, although it is unlikely to occur because Labour and the Liberal Democrats will oppose the measure, along with many Conservative MPs.
If it did go ahead, the amendment would send a clear message to Cameron. An amendment to a Queen's Speech has not happened since 1946 and the last time one was carried, in 1924, the prime minister was forced to resign.
While Cameron's Conservative Party continues to bicker over the EU issue, his coalition partner, Nick Clegg, derided the debate as distracting from more pressing issues.
And while government divisions over the EU are good news for the opposition Labour Party, small fissures are emerging there also.
A new group of 15 Labour MPs - called "Labour for a referendum" - launched on Monday with the aim of forcing their leader, Ed Miliband, to commit to a referendum on EU membership after the next election with a pledge similar to Cameron's.