The Tories could give British voters a say on 'key parts' of the Lisbon Treaty even if the document has been completely ratified before the next general election, Boris Johnson has said.
The Conservative Mayor of London said David Cameron would still need to 'give effect' to people's views even if the Treaty was ratified.
The Tory leader has only promised a referendum on the Treaty if it has not already been ratified by all 27 members of the European Union before he comes to power.
He is resisting pressure to explain what he would do, and whether there would be a referendum, if the Treaty had taken effect before then.
Mr Johnson said he thought it was 'bizarre' that people were being given no say over the prospect of former British Prime Minister Tony Blair becoming president of the EU.
'I do think there should be a consultation as soon as possible,' he told BBC Breakfast.
He admitted that if the Treaty had been ratified by the last two EU members, the Czech Republic and Poland, then it would be 'a different situation'.
'It will be a matter for William Hague and David Cameron to work out how to give effect to the consultation that I think the people want,' he said.
But, challenged that there would be no point having any consultation then because the Treaty would already be ratified, Mr Johnson said: 'That's not quite so and I think you will find that there are things that could be done, and it's certainly the case that you could put key parts of this Treaty to the people and you could certainly find out what people thought about it.
'I think there should be a referendum on this as soon as possible. I think we should do this before the process is concluded. I think it's unbelievable Labour are trying to get away with it.'
Asked which parts of the treaty the public could be given a say on, Mr Johnson went on: 'I would single out this idea of a European president, because it is so emblematic of what they are trying to achieve, and a European foreign policy'.
