The Foreign Secretary criticised "antics" in the House of Lords to delay proposed laws for an in-out referendum in 2017 and insisted it would remain Tory policy if it failed to reach the statute book.
Shadow chancellor Ed Balls said the Tories risked destabilising investment, the economy and business with its approach to the proposed EU referendum.
Labour and Liberal Democrat peers were accused of sabotaging the European Union (Referendum) Bill. The legislation now looks as if it will run out of parliamentary time.
Mr Hague said: "If David Cameron is prime minister after the next election, there will be a referendum."