Tories' European Union referendum bill explained
13 May 2013 Last updated at 23:04 BST
A draft parliamentary bill to allow for an in-out referendum on Britain's membership of the European Union by the end of 2017 is to be published by the Conservative Party on Tuesday.
The development comes amid growing ructions in the party over whether the UK should stay in or leave the EU.
Some Conservative MPs are seeking to force a vote on the issue as early as Wednesday.
The unexpected move is likely to be seen by David Cameron's critics as a major concession to eurosceptic backbenchers.
However, as Newsnight's Allegra Stratton explains, some of them have said they are not convinced by the move.