Prime Minister (born 19 June 1964)

Brexit campaign

In February 2016, Johnson endorsed Vote Leave in the "Out" campaign for the 2016 United Kingdom European Union membership referendum. He called Cameron's warnings about leaving "greatly over exaggerated". Following this announcement, which was interpreted by financial markets as making Brexit more probable, the pound sterling slumped by nearly 2% against the US dollar, reaching its lowest level since March 2009.

In April 2016, in an article for The Sun, in response to a comment by President Barack Obama that Britain should remain in the European Union, Johnson said an "ancestral dislike" of Britain owing to his "part-Kenyan" background may have shaped Obama's views.  Conservative MP Sir Nicholas Soames branded the comments "idiotic" and "deeply offensive". Several Labour and Liberal Democrat politicians condemned them as racist and unacceptable. In light of the remark, a King's College London student society revoked a speaking invitation it had extended to him. Conversely, both the Conservative Iain Duncan Smith and UK Independence Party (UKIP) leader Nigel Farage defended his comments.

Johnson supported Vote Leave's statement that the government was committed to Turkish accession to the EU at the earliest possible opportunity, contradicting the Britain Stronger in Europe campaign's view that Turkey "is not an issue in this referendum and it shouldn't be". Vote Leave was accused of implying that 80 million Turks would come to the UK if it stayed in the EU. When interviewed in January 2019, he said he had not mentioned Turkey during the campaign. On 22 June 2016, Johnson declared 23 June could be "Britain's independence day" in a televised debate in front of a 6,000-member audience at Wembley Arena. David Cameron, British prime minister at the time, specifically addressed Johnson's claim, publicly stating, "the idea that our country isn't independent is nonsense. This whole debate demonstrates our sovereignty."

Following the victory of the "Leave" campaign, Cameron resigned as Conservative leader and prime minister. Johnson was widely regarded as the front-runner to succeed him. Johnson announced he would not stand in the Conservative leadership election. Shortly before, Michael Gove, hitherto a Johnson ally, concluded that Johnson "cannot provide the leadership or build the team for the task ahead". The Telegraph called Gove's comments "the most spectacular political assassination in a generation". Johnson endorsed Andrea Leadsom's candidature, but she dropped out of the race a week later, leaving Theresa May to be elected uncontested.

David Cameron resigned as Prime Minister

following the victory of the "Leave campaign"