Can Martin Schulz succeed where Sanders and Corbyn failed?

Schulz (C) is the third male social democrat to take on a more conservative woman in the last 18 months.

(CNN)He's a former alcoholic, an ex-soccer player and he doesn't have a university degree.

Martin Schulz is not your average candidate for Chancellor.
But on September 24, the votes of millions of Germans will decide whether he will replace Angela Merkel, Germany's leader since 2005.
    Like America's Bernie Sanders and the UK's Jeremy Corbyn, he's a male social democrat taking on a more conservative female politician. And according to the polls, Schulz's chances don't look good.
    Could he do what Sanders and Corbyn failed to? Here's what you need to know about Merkel's challenger.

    Schulz the man

    Sanders and Corbyn were both viewed as outsiders trying to break into and shake up mainstream politics. And Schulz's early life certainly doesn't look like that of a typical career politician either.
    A serious knee injury shattered his childhood dreams of becoming a pro soccer player. He struggled with alcoholism and never went to university, working in a bookstore instead and later becoming mayor of his local town.
    It's a past he's happy to discuss. "When I left school early I really hit rock bottom," he said during a live YouTube interview with German voters on Tuesday. "That was the beginning of a crisis in my life."
    Schulz has been holding campaign rallies across Germany -- often attracting thousands -- in the run-up to the election.
    But for the past six years he's been president of the European Parliament -- and was a member of it for 16 years before that.
    "He's not a Corbyn or a Sanders," says Charles Lees, professor of politics at the University of Bath in England. "It's difficult for politicians who are basically insiders to suddenly adopt the mantle of the outsider without looking inauthentic."

    His campaign

    But Schulz did play the outsider card at the start of his campaign -- and successfully.
    Support for the Social Democratic Party (SPD) surged after he became its leader in January, and the party gained 20,000 members in the months that followed.
    "There was a huge amount of energy and hope among SPD supporters," recalls Andreas Jungherr, expert in political communication at the University of Konstanz in southern Germany. "Schulz was trying to use similar rhetoric to Sanders and Corbyn -- the rhetoric of hope and optimism."
    Countless memes were spawned, including a riff on the Obama "hope" poster and calls to "Make Europe Great Again."
    Schulz's election as leader of the SPD spawned the "MEGA" meme ("Make Europe Great Again"), riffing on President Donald Trump's campaign slogan.
    Key to the successes of Sanders and Corbyn was a strong grassroots campaign -- and that's vital to the SPD's efforts too.
    Tobias Nehren, who heads up the SPD's digital campaign, spent several weeks in the US before last year's election, getting top tips from activists who worked for Sanders and his rival Hillary Clinton.
    In rece