The current arrangements in the European Union are "simply not acceptable", Foreign Secretary Philip Hammond said as he confirmed he would vote to sever ties with Brussels unless there are significant reforms.
Mr Hammond said he expects the British people would vote to leave the European Union in the referendum promised by the Tories in 2017 unless the other members agree to changes.
He said powers have to come back to nation states, with Brussels accepting that where possible decisions should be left to individual countries, and the status of the eurozone has to be resolved.
Mr Hammond's appointment in the reshuffle, replacing William Hague, was seen as a boost to Tory Eurosceptics because of his stance on leaving if there is no change in the relationship with Brussels.
On BBC1's Andrew Marr Show, he confirmed his position has not changed even though he is now Foreign Secretary.
" I haven't changed my mind. If there is no change at all in the way Europe is governed, no change in the balance of competences between the nation states and the European Union, no resolution of the challenge of how the eurozone can succeed and co-exist with the non-eurozone; that is not a Europe that can work for Britain in the future.
"So there must be change, there must be renegotiation."
He said "the status quo is simply not acceptable, the status quo is not in Britain's interest", and he has made that position clear to European colleagues.
"If we have a Conservative government after the next election, there will be a referendum in 2017," he said.
"So the British people will decide. What I can tell and have told my European colleagues is that if the offer by our European partners is nothing, no change, no negotiation, I am pretty clear what the answer of the British people in that referendum is going to be."
Setting out his demands for change, he said: "There has to be a repatriation of powers to the nation states, a recognition - and this is not just a British demand, it's a demand from other countries too - that what can be done at national level should be done at national level.
"We should only do things at European level where it is absolutely necessary to do them at European level.
"Secondly, settling the relationship between the eurozone and the non-eurozone countries in a way that is fair to the non-eurozone and protects its interests."
He said there would be benefits in being out of the EU, but voters would have to decide whether those outweighed remaining in the 28-member bloc.
"That's the balancing decision that the British people will have to make," he said.
"I have no doubt that Britain gains enormously from being inside the European single market and what the British people will want to do is look at what is on offer, by way of change in Europe, by way of reform, and look at how far that takes us and balance the benefits of being in with the benefits of being out."
Mr Hammond also said there is a separate issue about the UK potentially withdrawing from the European Court of Human Rights - which is not an EU institution.
He said: "That's a separate agenda but also very important to the British people."
Mr Hammond also faced questions about his future as Foreign Secretary should the Conservatives remain in power after the 2015 general election.
He told Murnaghan on Sky News that reports he asked Prime Minister David Cameron if he was keeping the seat warm were not true and a "complete fabrication".
Asked if he would like to keep hold of the job should the Tories win the election, Mr Hammond replied: "We work as a team and I've always worked very closely with the Chancellor in particular.
"I will have the chance now to work with the Prime Minister and the Chancellor over the preparations for the European negotiations, which are going to be crucially important to Britain's future. That's something I will focus on over the next nine, 10 months.
"After the election, assuming that we win that election, we will then need to focus on the next phase - the renegotiation phase. It'll be crucially important and I'll be very happy to play any role that the Prime Minister asks me to play in that."