The new European constitution is not expected to be endorsed by parliament until early next year in a new signal that Tony Blair wants to delay confronting public scepticism.

Whitehall insiders said the bill to ratify the constitutional treaty and pave the way for a referendum was not now expected to become law until December or January, as the Tories gear up to challenge the government in parliament. The legislation will be published this week or next. But Foreign Office officials had originally been pressing for the bill to have its first reading before Christmas so it would reach the statute book before the general election expected in May.

They had wanted to avoid a parliamentary clash overshadowing Britain's EU presidency in the second half of the year.