David Cameron has outlined his four goals for reforming the UK's membership of the EU, including restrictions on benefits for people coming to the UK.
He said Britain faced a "huge decision" in the in/out referendum promised before the end of 2017.
But he said he was confident of getting what he wanted from reform talks.
Anti-EU campaigners say the talks are a "gimmick" - and the European Commission said the UK's benefits proposals could break free movement laws.
Mr Cameron formally set out his demands in a letter to the president of the European Council Donald Tusk saying four objectives lie at the heart of the UK's renegotiations:
*Protection of the single market for Britain and other non-euro countries
*Boosting competitiveness by setting a target for the reduction of the "burden" of red tape
*Exempting Britain from "ever-closer union" and bolstering national parliaments
*Restricting EU migrants' access to in-work benefits such as tax credits
Mr Cameron hit back at claims by former Tory chancellor Lord Lawson that the four goals were "disappointingly unambitious", saying they reflected what the British people wanted and would be "good for Britain and good for the European Union".
"It is mission possible and it is going to take a lot of hard work to get there," said the prime minister.
David Cameron sets out EU reform goals - BBC News
He said Britain faced a "huge decision" in the in/out referendum promised before the end of 2017.
But he said he was confident of getting what he wanted from reform talks.
Anti-EU campaigners say the talks are a "gimmick" - and the European Commission said the UK's benefits proposals could break free movement laws.
Mr Cameron formally set out his demands in a letter to the president of the European Council Donald Tusk saying four objectives lie at the heart of the UK's renegotiations:
*Protection of the single market for Britain and other non-euro countries
*Boosting competitiveness by setting a target for the reduction of the "burden" of red tape
*Exempting Britain from "ever-closer union" and bolstering national parliaments
*Restricting EU migrants' access to in-work benefits such as tax credits
Mr Cameron hit back at claims by former Tory chancellor Lord Lawson that the four goals were "disappointingly unambitious", saying they reflected what the British people wanted and would be "good for Britain and good for the European Union".
"It is mission possible and it is going to take a lot of hard work to get there," said the prime minister.
David Cameron sets out EU reform goals - BBC News
