Former mayor of London Boris Johnson on Thursday announced that he will not run for leadership of the Conservative party, on a day when two others launched their bids to take over Prime Minister David Cameron's post. Johnson was one of the most vocal “Leave” campaigners during the European Union referendum, which saw the British voting to stay out of the EU. Johnson’s announcement came after his rival Michael Gove said he would stand for party leadership. Gove said Johnson could not “build a team for the task ahead”.

United Kingdom Home Secretary Theresa May also launched her campaign on Thursday, and is considered the bookies’ favourite for the post, Financial Times reported. Johnson’s surprise announcement came at a time when the UK is reeling under political instability, and both its major parties, the Tories and Labour have been having leadership crises.

The referendum, or Brexit as it came to be known, has left Britain’s population more polarised than ever before, led to a slew of racist attacks and caused its markets to plummet. As if to address this, Johnson said, “This is our chance to unite our country and our society. It is vital now in the Conservative party that we bring together everybody that campaigned for both the Remain and Leave sides.”

Cameron, who had made the call for the referendum and had strongly favoured the “Remain” side, said he would step down from his post after 52% of the UK voted to “Leave”.