The former Lib Dem leader joined a group of Remain MPs to put forward 10 demands to the Prime Minister, describing the list as a “Brexit contract between the UK Government and the British people”.
However, the ardent Europhile warned there was “no chance” of a deal being struck between the UK and the bloc by 2019.
Speaking at an event for the cross-party Open Britain group on Tuesday, he said: “That everything is going to be signed and sealed and done in two years, it ain’t.
“That we’re going to have sparkly new trade agreements worth twice the value of the European Union before we’ve even left, we won’t.
Nick Clegg painted a gloomy picture on the eve of Article 50 begin triggered
That everything is going to be signed and sealed and done in two years, it ain’t
Alluding to the Government’s promise to try to secure a free trade deal with the bloc, he sarcastically added: “And now apparently we aren’t even going to pay any money at all.”
The Prime Minister has vowed to walk away from the negotiating table with Brussels if she is not satisfied with the offer.
Mrs May argued “no deal is better than a bad deal” – a call backed up by many Leave campaigners.
The former Lib Dem leader warned a trade deal would not be complete by 2019
However, sitting alongside Mr Clegg, former minister Nicky Morgan insisted she would try and bat away any pressures to leave the EU with "no deal".
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“There will be agitation for early departure,” she said. “For realisation, the Europeans are not serious, we should walk away, I will do everything in my power on my benches to make sure that does not become a reality.”
It’s understood the process will formally begin with a letter from the Prime Minister to Donald Tusk, the President of the European Council on Wednesday.
Once received, the firing gun is triggered for the UK’s two-year exit from the Brussels club to begin.
Open Britain vowed to hold the Government to account during the Brexit process Remoaners Club: These people hate Brexit! Mon, January 16, 2017
Remainers are finding it hard to accept Brexit.
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Open Britain, which claims to represent the 48 per cent of voters who opted for Remain, has listed 10 promises for the UK Government to deliver on.
The demands include; the same benefits outside the single market, new trade deals ready to sign on day one and major savings from the EU budget.
The group said: “Now that Article 50 is being triggered, people will expect these promises to be delivered: this is the Government’s Brexit Contract with the British people.
“As patriots, we want the best for our country. As realists, we fear the Government’s Brexit Contract may not deliver that outcome. And as democrats, we think that should be a judgement people and Parliament are able to make.”