In the French presidential primary on Sunday, Francois Fillon of the Republicans party soundly defeated front-runner Alain Juppe, winning close to 67 percent of the votes.

Two weeks ago, a landslide victory for the apparent underdog seemed out of the question. It had long been expected that Juppe, the mayor of Bordeaux and a former prime minister under President Jacques Chirac, would beat the other front-runner, former President Nicolas Sarkozy, in a second-round runoff. Instead, Fillon, a former prime minister under Sarkozy, emerged from the first round with a commanding lead, winning 44 percent of the vote. The outcome was humiliating for Sarkozy, who received just a little over 20 percent support, and effectively ended his political career.

For many observers, the vote invoked the specter of June's Brexit referendum and U.S. President-elect Donald Trump's victory earlier this month. Opinion polls placing Fillon as a distant third were proven wrong, partly because many voters seem to have made up their minds just days before the vote. Social media were also credited, again, with playing a key role. In the last debates before the vote, Fillon presented himself as a credible alternative to Juppe and Sarkozy.