UK referendum on EU constitution
Agreeing to a referendum would mark a complete u-turn in government policy. Until now, ministers have been arguing that the constitution does not make the fundamental changes which would warrant a referendum and that it could simply be ratified by parliament.
But opponents argue that the constitution by its very name is different. They say it's likely to compromise Britain's sovereignty. The strongest opposition has been from the Conservative party, although a significant group within the governing Labour party are sceptical too.
There is, though, a broader coalition in favour of a referendum, including some who support the constitution.
The third party, the Liberal Democrats, for example, believe a nationwide vote would be the best way to make the pro-European argument.
The government will clearly have a struggle on its hands to win over an argument which has been dominated by a Euro-sceptic press and they wouldn't want to lose a referendum shortly before a general election which is expected in a year's time.