David Cameron has suggested that membership of the European Union is the most important decision British voters could have to take at the ballot box in their lifetimes.
His comments came as he set out his demands for EU reform.
The Prime Minister has pledged to hold an In/Out referendum on the EU.
But the vote will only come after a renegotiation of the UK's relationship with the EU.
Mr Cameron denied his plans were "Mission Impossible".
And he said the issue was "perhaps the most important decision that the British people will have to take at the ballot box in our lifetime".
The outcome of the EU vote could lead to a second Scottish independence vote.
SNP leader Nicola Sturgeon has suggested an 'Out' result could be a trigger for a second referendum.
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