British PM, David Cameron
David Cameron has said he is confident of getting the changes he wants in the UK's relationship with Europe.
He told BBC Radio 4's Today he wants a "fresh settlement" with Europe and would then seek "consent" from Britons.
Although he declined to say this would mean a referendum, he said it would be done in a "straightforward way".
He dismissed business and political critics who warn uncertainty caused by the prospect of a future referendum could put British business at risk, reports the BBC.
Labour said Cameron was putting party unity ahead of inward investment, jobs and growth.
Cameron is expected to announce his plans - including a referendum after the next election - in detail in a long-awaited speech on the UK and Europe next week.
He has faced pressure to hold a referendum on Europe and has been criticised by some in his own party for not doing more to get powers back from the EU to the UK.
But others, such as pro-European Tory peer Lord Heseltine, have warned a referendum would jeopardise the UK's business prospects.
Cameron said he wanted the UK to remain within the EU, but said there was a need to redefine the relationship in light of moves towards further integration by countries using the single currency.
"Europe is changing and the opportunity for us to lead those changes and make changes that will make our relationship with Europe more comfortable, I think, are absolutely there.
"I am confident we can do that - a fresh settlement and then fresh consent for that settlement," he said.
Lord Heseltine and a series of leaders of large British businesses have said the uncertainty caused by the idea of a future referendum which could lead to the UK's exit from the EU, put at risk Britain's relationship with Europe and could cause problems for British business.
But the PM said the EU was already in the process of change because of the recent euro area crisis: "This debate is happening anyway."
"You have a choice as politicians - do you get out there, lead that debate and make the changes that will be right for Britain - and I would argue right for Europe - and then give people a choice about that, or do you stick you head in the sand and hope the debate will go away?"