The former deputy PM blasted Prime Minister Theresa May for delaying the UK’s withdrawal from the European Union.
He said in an interview with The Times: “I want to stop it Brexit — yes, absolutely. The transition period is just a euphemism for delay.
“I think it is the most undignified act of humiliation that I can remember in my lifetime.”
Britain and the EU agreed a Brexit transition deal, paving the way for future UK-EU trade talks, after EU leaders formally backed the agreement at a summit in Brussels on Friday.
Jean-Claude Juncker, the president of the European Commission, said the guidelines were adopted by EU leaders in under half a minute.
EU leaders agreed that the transition period would start after the Brexit deadline on March 19 next year, and would last until the end of 2020.
During that time period, Britain’s membership of the single market and customs union will be frozen, giving businesses time in preparation for the UK exit, but the country will give up its EU voting rights.
The deal also laid bare the bones of the future UK-EU relationship, including cooperation on security, foreign police and crime, and a free trade agreement.
Mrs May said: “This gives certainty to people and businesses, it gives them the clarity to plan for their future and it ensures that they will only have to make one change when we enter into our future relationship.
“I believe there is a new dynamic now in the negotiations. We are approaching this with a spirit of cooperation and a spirit of opportunity for the future.”
But Sir Nick, who lost his position as deputy prime minister and saw the Liberal Democrats being crushed at the 2015 election, criticised Brexiteers for their empty promises.
He said: “Brexiteers have literally abandoned every single one of their promises — lower prescription charges, smaller class sizes, complete control over fisheries, complete control of our borders, £350 million for the NHS.
“At that point I think it is perfectly OK for MPs to say, ‘Hang on a minute, I’m sorry but this is not what you said would happen’.”
And Sir Nick thinks the EU would allow the UK to delay its departure by extending the Article 50 process.
He explained: “I’m totally satisfied now that I’ve spoken to most of the governments across the EU that, with some grumbling, the centre of gravity remains — ‘if there’s a chance of you guys rethinking this, we will do what it takes’.
“I’ve spoken to Macron about it and I definitely think he would, Angela Merkel too . . . I think most grown-ups across the EU know that a EU with Britain in it is much stronger.”