ANY DOUBT that the West is experiencing a profound political crisis can be dispatched with a glance at the final polls for the first round of France’s presidential election Sunday. They show what looks like a four-way dead heat for the two places in a May 7 runoff. Two of the candidates, the far-rightist Marine Le Pen and the far-leftist Jean-Luc Mélenchon, represent political extremes that reject virtually everything that France has stood for since the founding of the Fifth Republic in 1958. The mere possibility that they will be the country’s choice in the second round ought to be heart-stopping for anyone who hopes the West’s core liberal values will survive the wave of popular discontent that already has driven Britain’s vote to leave the European Union, as well as the election of Donald Trump.

For those disinclined to revolution, the best choice is Emmanuel Macron, a 39-year-old former economy minister for the current Socialist government who founded a new, centrist party a year ago. Striking an upbeat tone that is starkly at odds with most of his competitors, Mr. Macron proposes sensible reforms of France’s stagnant, statist economy, which has produced double-digit unemployment since 2010. He’s an unapologetic defender of free trade, gay rights and France’s place in the European Union. In contrast, the next-most-centrist candidate, conservative François Fillon, has adopted harsh anti-Islam and anti-immigrant postures and, like Ms. Le Pen and Mr. Mélenchon, is both anti-American and soft on Russia’s Vladi­mir Putin.

Mr. Fillon, in turn, looks palatable compared with Ms. Le Pen, whose National Front is France’s modern version of fascism. Though she has sought to project a more moderate image than her father, a Holocaust doubter and former presidential candidate, Ms. Le Pen tooted her own dog whistle recently by denying French responsibility for the deportation of Jews to death camps. She would pull the country out of the euro, and probably the European Union, declare a moratorium on immigration and wage cultural war against Islam. Unfortunately, the shooting of police officers on Paris’s Champs-Elysee on Thursday, which the Islamic State claimed responsibility for, could drive some undecided voters her way.

Then there is Mr. Mélenchon, a Trotskyite throwback who has surged in the polls in part because of futuristic tactics such as speeches-by-hologram. He would pull France out of NATO and ally it with Cuba and Venezuela; he says his “is not a Western country.” Given his economic proposals, including a 100 percent income-tax bracket and massive new government spending, he would be as likely to destroy the European Union as Ms. Le Pen.

If Mr. Macron somehow survives this ugly scrum (there are seven other minor candidates), he will be a favorite to win the presidency in a second round; E.U. and NATO leaders, as well as financial markets, will breathe a sigh of relief. A Macron government could, in concert with what is likely to be the centrist majority emerging from German elections this fall, reinforce the more mainstream foreign-policy course lately adopted by the Trump administration. For now, however, the catastrophic alternatives cannot be ruled out — and even if they do not come to pass, France will have offered another sobering view of the depths of the West’s discontents.