London:Leading Brexit campaigner and former London Mayor Boris Johnson on Thursday ruled himself out of the race to be next Conservative leader and Prime Minister, soon after Justice Secretary Michael Gove entered the competition to succeed incumbent David Cameron. Besides Gove, Theresa May, Stephen Crabb, Liam Fox and Andrea Leadsom were confirmed as official Tory leadership contenders. The contest follows British Prime Minister David Cameron's announcement to quit following the EU referendum result, which saw Britain voting to leave by 52 per cent to 48 per cent of remain. Johnson's unexpected -- and dramatic -- announcement that he would not contend for Tory leadership, leaves Home Secretary Theresa May as hot favourite to be the next British Prime Minister. Johnson told media in London that the next Conservative leader would have to unify his party and ensure that Britain stood tall in the world. "Having consulted colleagues and in view of the circumstances in Parliament, I have concluded that person cannot be me," he said. Earlier, Gove shocked the political circuit with his intention to become the Prime Minister. The former education secretary said that he does not believe Boris can "provide the leadership" for the task ahead to get a fair deal for Britain in talks with European Union. The journalist-turned-politician had repeatedly said he had no leadership ambitions. "I respect and admire all the candidates running for the leadership. In particular, I wanted to help build a team behind Boris Johnson so that a politician who argued for leaving the European Union could lead us to a better future," Gove said in a statement. "But I have come, reluctantly, to the conclusion that Boris cannot provide the leadership or build the team for the task ahead. I have, therefore, decided to put my name forward for the leadership. "I want there to be an open and positive debate about the path the country will now take. Whatever the verdict of that debate, I will respect it. In the next few days I will lay out my plan for the United Kingdom which I hope can provide unity and change."