The decision by British Prime Minister David Cameron to step down later this year puts former London Mayor Boris Johnson among the top contenders to succeed him.
So, just who is Johnson?
The Conservative politician was London mayor from 2008 to early this year and provided a leading voice in the British campaign to leave the European Union. The view pitted him directly against Cameron, a party fellow and a proponent of remaining in the economic and political bloc.
Cameron announced early Friday that he would step down as it became apparent that the British people had voted to break from the EU. The result shocked global markets, which had largely bet that the U.K. would vote to remain.
Johnson, a member of Parliament for Uxbridge and South Ruislip in Greater London, appears to be on the early short list to succeed Cameron. Bookmaker Ladbrokes listed Johnson as the favorite, ahead of Home Secretary Theresa May and Justice Secretary Michael Gove, according to Reuters.
Johnson told CNBC earlier this month that the referendum marked a "once in a generation chance to take back control from an institution that is out of control, spending ever-growing quantities of British taxpayers' money." He cited a perceived loss of control over taxation and borders as reasons to break from Europe.
"I think that over time the U.K. economy would get a lot of dynamism from the removal of so much of the regulation and the inappropriate law that holds us back," he said.
He also contended that Britain had lost control of some aspects of its judicial system because of the structure of EU institutions.
After the referendum vote, though, Johnson expressed some caution about breaking from Europe too quickly and attempted to assuage Britons who voted to remain. He said the U.K. "cannot turn (its) back on Europe" because it is "a part of Europe," according to the BBC.
Johnson earned a reputation as a colorful and sometimes controversial figure during his time as London's mayor. He often drew attention for public displays, like when he went down a zip line in a suit waving British flags.
He has also drawn ire for certain remarks during his time in the public eye. Earlier this year, Johnson implied that U.S. President Barack Obama's "part-Kenyan" heritage led him toward anti-British sentiment, according to The Guardian.