The call for unity may favor Macron. Benoît Hamon’s victory in the Socialist Party primary last month, in which he defeated Valls, the favored candidate, signaled a strong rebuke of the party’s direction under Hollande, the deeply unpopular president who declined to seek re-election after his approval rating slumped to record lows. Hamon’s has been dubbed the “French Jeremy Corbyn,” for the leader of Britain’s Labour Party, or the “French Bernie Sanders,” for the U.S. senator from Vermont. Critics say the Socialist candidate’s politics make him similar to Jean-Luc Mélenchon, the Left Party candidate, whose political faction mainly comprises former Socialists. Mélenchon finished fourth in the 2012 presidential election.

Dr. David Lees, a researcher on French politics at Warwick University in the U.K., told me the dissimilarity between the left-wing candidates could cause more centrist Socialist voters to look elsewhere.

“Macron will be the real winner of the Hamon appointment,” Lees said. “The real issue here lies with the people who are more centrist in the Socialist party, and I suspect what they’ll do now is move towards Macron as a clear centrist candidate and somebody who appeals to left and right, without the same kind of populism and anti-immigrant rhetoric of Marine Le Pen.”

But Macron doesn’t just stand to gain votes on the left. On the right, Republican candidate Fillon’s campaign has been embroiled by allegations he paid his wife, Penelope, and his children a nearly 1-million euro ($1,067,930) salary over more than a decade for being his parliamentary assistants—a job some alleged they did not perform. The center-right candidate, who campaigned on a platform of cutting wasteful spending, reaffirmed he did nothing illegal, and said he would only drop out of the race if a formal investigation were launched. Still, the allegations have hurt him. Fillon, who was originally favored to lead the first round and beat Le Pen in the second round run-off, slumped to third place in the first round in a recent IFOP poll; the poll shows Le Pen finishing first and Macron second.

“It’s been hugely detrimental to his relationship with voters,” Lees said, adding that while traditional Catholic conservatives may likely still vote for Fillon, “center voters who might have voted for Fillon, they might now vote for Macron.”

Macron, though, is not without challenges. Despite presenting himself as an accomplished investment banker and an energetic political outsider, his government experience includes pushing through a number of unpopular business reforms, chief among them his signature Macron Law, which the government, due to its lack of support, had to force through by decree. The law aimed to boost economic growth by, among other things, allowing employers to more easily negotiate salaries and working hours, as well as enable businesses to open more Sundays per year—a departure from French tradition that Sundays should be a day of rest. Moreover, Macron’s independent candidacy runs against the French establishment—without which no presidential candidate has ever won.