The House of Parliament has voted in favour of Britain signing up to the EU constitution in its first vote on the issue.
The Labour Party's large majority ensured approval of a bill ratifying the treaty agreed during Ireland's presidency of the EU last year by 345 votes to 130.
While the bill must pass further parliamentary stages, the biggest obstacle will be a referendum likely to be held in 2006.
Prime Minster Tony Blair is almost certain win the general election due to called in May but he will face a much tougher task convincing the "eurosceptic" British public it should approve the constitution.
The Conservatives are leading the charge against it saying it will seriously compromise the country's sovereignty and is another step towards a federal European superstate.
Most polls show a majority of Britons oppose the treaty and a 'No' vote could even force Blair out of office, analysts say.
PA