Emmanuel Macron’s outsider bid to transform France’s political system was bolstered yet again on Sunday, as his party and supporting allies won an overwhelming majority in the second and final round of legislative elections, securing 350 out of 577 seats. Founded just 14 months ago, the president’s centrist En Marche! party defied expectation in the general election last month, skirting the left-right divide that has dominated French politics for decades, and defeating nationalist-populist rival Marine Le Pen with the promise of tolerance and renovation. For the international community, wavering in the wake of the Brexit vote and Donald Trump’s volatile entrance onto the world stage, Macron served as a poignant symbol of the progressive center’s ability to withstand the ominous march of the far-right.

Now, with his conquest of parliament complete, Macron faces the dual challenge of reinventing French politics, seemingly from scratch, while serving as the innovative face of a powerful but untested party. Over the past several weeks, Macron has fostered that image, casting himself as the European version of a maverick Silicon Valley C.E.O. He rules with a Jupiterean authority, from the top down, and has garnered plaudits for his firm approach to Vladimir Putin and Donald Trump. His famously flesh-draining handshake with the American president, he briskly explained to Journal du Dimanche afterward, was purposefully weighted with a symbolic, and easy-to-interpret, meaning.

Macron’s ascendancy appears all the more starry when compared to the volley of political convulsions in neighboring Britain. Theresa May’s snap election—another Tory gamble that spectacularly backfired—has left the prime minister without a mandate, fielding a nightmarish exorbitance of headlines, battling rumors of party mutiny, and attempting to navigate the beginnings of the Brexit negotiations, which start today, despite no one being any clearer as to what is being negotiated or who is negotiating what. This kaleidoscopic web of political complexity is tangled with a series of tragedies that has befallen the nation, most recently culminating in the Grenfell Tower fire in which the death toll has climbed to 79, and last night’s terror attack, which saw a van drive into a crowd of worshippers after they'd left a mosque in North London. As May’s mantra of strength and stability implodes, Macron seems to embody it with deft confidence.

But if Macron’s rise to victory is contrasted by the stark contortions gripping the U.K., his overarching challenge is how to translate a presidential election based on personality into the everyday machinations of politics. Although his party secured a majority, it did not win as many seats as initially expected, and turnout was an underwhelming 45 percent of registered voters—the lowest number for the second round of a parliamentary election in the history of France’s Fifth Republic. Macron, for all his youthful elan, received little enthusiasm from young voters, who flocked to Le Pen and leftist Jean-Luc Mélenchon.

The reasons for this are myriad. Voters remain fatigued after the histrionic battle between Macron and Le Pen. They are alienated by the shape of a new political narrative. But, with the majority of abstaining voters coming from working class and lower-income backgrounds, the low turnout underscores the battle that Macron must now fight—to uplift those most affected by the years of depression and unemployment that have plagued France, whom he least inspires. The biggest obstacle impeding his presidency will be to appease those instinctively suspicious of his centrist, global, pro-European Union politics, and to try to prevent losing voters to the far right which, although disjointed, has not been defeated. Indeed, Le Pen won a parliamentary seat for the first time last night, and her National Front Party won seven.

Macon has pledged to revitalize politics, to streamline the state, and loosen labor laws to promote flexibility for businesses. His latest victory will give him the mandate needed to push through his promised economic reforms. The success of these reforms will be scrutinized keenly not just at home, but abroad too, specifically by Angela Merkel, to whom Macron needs to demonstrate economic expertise if he wishes to foster a crucial alliance with Germany. The stakes are high and Macron, a political neophyte navigating a political minefield, must rely on an untested new array of National Assembly members, many of whom are political neophytes, too. The president’s success is staggering, and the positive optimism of his politics critical, especially at a moment when a struggling and bruised U.K. is entering Brexit negotiations. Now, Macron needs to show that he can transform his poetics into pragmatism.