The former Foreign Secretary is the favourite to be the next Tory leader, after the resignation of Theresa May earlier this month. After securing 114 MPs’ votes in the first ballot, he is expected to make it through the subsequent rounds to the final two, which will be decided by Tory Party members. He will be appearing on the BBC debate tonight, alongside his 5 competitors.
Mr Johnson has experienced the workings of the EU first hand, working as a Telegraph Brussels correspondent between 1989 and 1994.
These years saw the drawing up and signing of the Maastricht Treaty, a landmark step in European integration.
One of the key figures behind the treaty was former European Commission President Jacques Delors.
Known to be pro-integration, Mr Delors oversaw the founding of the modern day European Union.
READ MORE: Boris Johnson: Tory leadership favourite’s ‘breathtaking weakness’
According to Mr Johnson, a key consideration in this plan was the break-down of the Soviet Union.
After the Berlin Wall fell in November 1991 and the USSR fell apart, Germany was reunited.
In a 2003 Telegraph article Mr Johnson claimed there were fears that Germany would now “dominate” Europe.
He wrote: “A means had to be found to control Germany, to moderate her new strength.
“In Paris, the answer was to build up the institutions of the EEC, to the point where Germany was ‘locked in’ to a federal economic and political union.
“Delors hoped his new glorious entity would, in some sense, fill the vacuum left by the collapse of the Soviet Union.
“Europe would not be adversarial to America, or certainly not hostile, but she would supply the other pole of influence in a bipolar word.”
Mr Johnson claims that, in this way, the Maastricht Treaty, signed in February 1992 created a new union to fill the power vacuum left by the Soviet Union and, in doing so, contain Germany.
His articles about Maastricht are said to have exacerbated tensions between Eurosceptic and Europhile Tory factions that were tearing the party apart.
Lord William Rees-Mogg – Jacob Rees-Mogg’s father – even went to court in a bid to stop the treaty becoming law as he became a leading figure among the Maastricht rebels, alongside the likes of John Redwood and Bill Cash.
It was also the moment Nigel Farage lost faith with Tory policy and Ukip was founded.
Mr Johnson has pledged to take the UK out of the EU by October 31, deal or not, if he becomes the next leader.
He will debate fellow contestants Jeremy Hunt, Sajid Javid, Dominic Raab, Michael Gove and Rory Stewart in a TV debate tonight.
Mr Hunt came second in the first ballot with 43 MPs voting for him.