The Conservatives would change the law to ensure a referendum is held every time ministers agree to sign away powers to the EU, William Hague says.
Critics say the treaty is the constitution by another name
The shadow foreign secretary told the Tories' conference that the permission of the British people should be sought before any EU treaty was ratified.
The change would mean amending the 1972 European Communities Act.
The Tories want a referendum on the EU Treaty. Prime Minister Gordon Brown says a poll is not necessary.
Mr Brown says the EU Treaty is not the same as the constitution rejected by voters in France and Holland, on which a vote was promised in Labour's 2005 manifesto.
But Mr Hague told Tory representatives in Blackpool the claim "is one of the most bare-faced and deliberate misrepresentations in the modern annals of political deceit".
"The importance of it is hard to overstate: the creation of permanent President of the European Council, the appointment of an EU foreign minister in all but name, the abolition of 60 of our national vetoes," he said.
It also includes a provision for the abolition of almost every remaining veto without any further treaty negotiation or proper ratification by Parliament, he said.
Mr Hague said all three major parties promised a poll at the last election in their manifestos, but "only the Conservative party is still true to its word".
The Tories would "explain the treaty's significance" over the next few weeks and "why its importance merits the British people's judgement in a national referendum", he said.
"And I can tell you today that we will go further: the next Conservative Government will amend the 1972 European Communities Act so that if any future government agrees any treaty that transfers further competences from Britain to the EU, a national referendum before it could be ratified would be required by law.
"And so, as we campaign for the referendum the people of our country were solemnly promised, we are fighting not only for them to have their say now, but for them always to have their say."
Mr Hague said the Tories would be fighting for an EU that "can never replace the just claim of national government to be the linchpin of democratic consent".
Gordon Brown says that a referendum on the treaty is not needed because the UK's "red lines" had been successfully defended.
He has also pointed out that the Maastricht treaty was agreed without the then Conservative government holding a referendum.
Lib Dem leader Sir Menzies Campbell also opposes a referendum on the treaty. However he has called for a referendum on the wider subject of the UK's membership of the EU.