London Mayor Boris Johnson will campaign in favor of the so-called Brexit, according to media reports.

MOSCOW/LONDON (Sputnik) – London Mayor Boris Johnson, seen as among the favorites to succeed Prime Minister David Cameron as the leader of the Conservative Party, will campaign for the United Kingdom to leave the European Union, British media reported Sunday.

"Boris WILL campaign to leave the EU —Huge boost for Out," BBC political editor Laura Kuenssberg tweeted, adding that Johnson’s official announcement would follow in the evening.

Boris WILL campaign to leave the EU —Huge boost for Out, big blow for number ten altho expected — more soon — Laura Kuenssberg (@bbclaurak) February 21, 2016

Johnson was widely expected to campaign in favor of the so-called Brexit, joining the ranks of Work and Pensions Secretary Iain Duncan Smith, Justice Secretary Michael Gove and a number of other allies.

Britons are scheduled to go to the polls on June 23 for an in/out referendum, after Cameron and 27 of his European colleagues negotiated a deal to grant the UK special status within the bloc.

Cameron sought to revise the terms of his country's EU membership, focusing on four main issues: shifting power away from EU authorities to the UK national legislature, exempting Britain from the EU "superstate" principle, stripping the euro of the the single official EU currency status, and protecting the British economy by keeping eurozone members away from non-eurozone countries’ affairs.

After reaching the deal, Cameron argued that the United Kingdom would be "safer and stronger" within the European Union.