David Cameron has said good progress has been made in talks about EU reforms.
He was asked by ITV News Europe Editor James Mates how he rated the chances of getting a deal done by February and a subsequent referendum.
The Prime Minister replied "nothing was certain in life, or in Brussels".
But he added there was a "pathway" to striking a deal when the member states next meet again in February.
Cameron said: "It's going to take a lot of hard work, but there is a lot of good will and momentum.
"With that spirit, I will do everything I can to get this fixed because I want Britain to have a better deal, because this is what it is all about.
"And I think we have taken a step towards a better deal tonight."
Poland could drop fierce opposition on plans to cut EU benefits in return for a deal on new NATO bases, the country's foreign minister said.
Britain leaving the EU risks leading to the break-up of the UK, while "gravely weakening" the continent's security, William Hague warned.
The fact is if Britain leaves the EU a new relationship would have to be forged - we've no idea what that relationship would look like.