Mr Barnier has played an important role in shaping the future relationship between the EU and Britain. Only a month after the UK voted to leave the bloc, Brussels announced he would be the EU’s chief Brexit negotiator, under Article 50 of the Treaty on European Union. For the 2020 trade talks, Mr Barnier was once again the main negotiator and despite months of tensions, the two sides reached an agreement on Christmas Eve.
Now, there is mounting speculation the French politician might be mulling a possible bid in next year’s presidential election, as he announced last week he was setting up a political faction under the name “Patriot and European”.
As Mr Barnier is being closely watched by French President Emmanuel Macron’s camp, as he would eat at the pro-European, centre-right electorate, one of his most controversial tweets has resurfaced.
In 2015, the French politician, who at the time was serving as unpaid special adviser to former President of the European Commission Jean-Claude Juncker, suggested he did not care about the outcome of referendums.
He tweeted: “Whether it’s a yes or a no, the eurozone will have to continue reforming: governance, banking resolution, taxation, eurobonds, treasury.”
At the time, the leaders from the euro area member states had just reached an agreement that paved the way to a third Greek bailout.
Mr Barnier is not the only EU politician to have put forward such claims.
In 2005, Mr Juncker, who at the time was Luxembourg’s Minister for Finances and President of the Euro Group, was pushing for a European Constitution.
On May 29 of that year, France held a referendum to decide whether it should ratify the proposed Constitution but, ahead of the vote, Mr Juncker admitted he would ignore the result if it did not go the way he intended.
He said: “If it’s a Yes, we will say ‘on we go’, and if it’s a No we will say ‘we continue.'”
Following the No votes in France and the Netherlands, Mr Juncker also claimed that, in reality, voters had actually supported a deeper European integration.
His remarks were met with outrage by eurosceptics, who suggested that the EU elite was in denial over the public hostility towards the bloc.
In the end, as the European Commission President predicted, eurocrats ignored the results of such popular votes and the European Constitution was subsequently rebranded as the Lisbon Treaty and passed in 2007.
In an exclusive interview with Express.co.uk, Frexit campaigner Charles-Henri Gallois criticised the EU for the way it deals with referendums and general elections.
He said: “Theresa May was a Remainer, so she was not negotiating to leave.
“What she came up with was a bad agreement and those were bad negotiations.
“The losers didn’t want to accept the fact they lost. Simple as that.”
Mr Gallois added: “We have seen in the EU how this is always the case.
“It was the same in France in 2005.
“We voted against the European Constitution but they ignored our vote.
“They simply rebranded it the Lisbon Treaty.
“The EU doesn’t accept the result of elections if they don’t go the way they want them to go.”
Reform UK Party leader Nigel Farage famously claimed this was the moment he lost faith in the European Union and started to despise it.
Speaking on his LBC show, Mr Farage said: “In 2005, the European Union had produced its own constitution.
“The first proper blueprint – the first genuine admission that what they were building wasn’t a free trade zone, it was a state and they put it to referendums.
“The French rejected it, the Dutch rejected it and many other people, had they had the chance, would have rejected it.
“And what did the EU do? Did they learn the lesson? Did they say ‘Oh well obviously people don’t want a state with a flag, an anthem and an army.’ Did they row back? No, they rebranded it as the Lisbon Treaty.
“They forced it through without giving the French and Dutch another option. The Irish voted against it but were forced to vote again.
“From that moment, I have been an enemy of the entire project.”