When Boris Johnson announced in February that he would back the campaign to leave the European Union, it transformed the debate. Johnson is popular with the public and within his party. By becoming the official head of Vote Leave, he gave the weight of the establishment to a campaign previously spear-headed by fringe political figures such as Nigel Farage and George Galloway.

"I will be advocating Vote Leave - or whatever the team is called, I understand there are a lot of them - because I want a better deal for the people of this country, to save them money and to take control. That is really what this is all about," he said at the time.

Prime Minister David Cameron had reportedly pleaded with Johnson for weeks to stay with the government and back Remain. Polls had shown that Johnson's support for Leave would have a significant impact on the polls, an effect that appears to have been borne out.

"Unlike most politicians, he talks in a way that is distinctive and appeals to people across the political spectrum," says Adam Bienkov, deputy editor of politics.co.uk and a long-time reporter on London. "He's not your typical politician, he's willing to say thing others aren't willing to say. Sometimes it backfires, but it certainly doesn't lead to him being forgotten - people know who he is and he's the most popular politician in the UK."

Many believe that Johnson's decision to back Leave was an opportunistic ploy motivated not by genuine conviction but by the desire to boost his chances of becoming Conservative leader.

"From a tactical point of view it makes sense. If Leave wins then he can go for David Cameron's job, riding as the de facto leader of the Tory Leave campaign. If Remain wins he's someone who the euroskeptic Tory grassroots members will see as on their side," says James Bloodworth, political commentator and author of "The Myth of Meritocracy." "It's almost a win-win for him, though there is a risk that his star will wane if Cameron keeps him on the backbenches till 2020."

Now that Britain has decided to leave the EU, Cameron will almost certainly stand down. Johnson currently appears to be the most likely candidate to succeed him. Who exactly is this colorful politician, and what is behind his enduring appeal?

Winning streak

Before entering politics, Johnson had a successful career as a journalist, working at "The Times" and the "Daily Telegraph," and becoming editor of the Spectator in 1999. He stepped down from this role in 2001 to enter Parliament as an MP, but has always continued to write columns for the Telegraph and Spectator. (During his eight years as Mayor, he earned substantially more from his journalism than from his political salary). After eight years as Mayor of London, he returned to Parliament in 2015 in the safe Conservative seat of Uxbridge and South Ruislip.

Johnson has made a name for himself for his outrageous comments and blustering humor, seen by many as an antidote to the often staid world of Westminster politics. "Voting Tory will cause your wife to have bigger breasts and increase your chances of owning a BMW M3," he said during the 2005 general election campaign. A video of Johnson getting stuck on a zip wire in east London became one of the most enduring images of the 2012 Olympics.

"He's very charismatic and it shines through," says Bloodworth. "In the Conservative Party itself, I think the appeal is quite easy to fathom. Boris is a winner, but he also hits a lot of the Tory party's ideological notes too - a rare combination."

When Johnson beat Labour's Ken Livingstone to become the Mayor of London in 2008, it was the Conservative's first major, high-profile election success since before Tony Blair's triumphant entry into Downing Street in 1997. Johnson defeated Livingstone again in 2012, cementing his reputation as a winner.

Future prospects

Despite his bumbling exterior and penchant for inappropriate remarks, it has long been speculated that Johnson wants to displace Cameron, a fellow graduate of Eton school and Oxford University. Yet many have questioned his legacy.

Transport fares soared under his leadership and there were numerous long-running disputes with transport unions.

"When you look at his record as mayor, he hasn't done a huge amount," says Bienkov. "At the last election, he didn't even promise a great deal - there was very little policy wise in his manifesto. Over the last four years, there's been a kind of stasis at City Hall. You could say he's been more interested in other things: writing books, for example."

When Johnson stepped down as mayor, most national papers published affectionate lists of his most memorable gaffes and quips. While his outrageous comments - he once described the town as Portsmouth as "too full of drugs, obesity, under-achievement, and Labour MPs" - are popular, they might not work so well for a prime minister.

"I don't think he'd be a particularly good leader," says Bloodworth. "He makes too many gaffes. Once you're the leader of a party, it's much harder to bluff your way through."