Russian opposition leader Alexei Navalny. (Evgeny Feldman/AP)

VLADIMIR PUTIN boasts of popularity ratings that Western leaders, Donald Trump included, can only dream of — 85 percent and above since Russia's invasion and annexation of Crimea in 2014. Yet Mr. Putin remains unwilling to test those numbers against real competition. On Monday, the state election commission banned his most popular opponent, Alexei Navalny, from running in the presidential election scheduled for March 18 — meaning that Mr. Putin will face no serious opposition to obtaining another six-year term.

Mr. Navalny, who has attracted a broad following across Russia by campaigning against corruption, was proscribed on the basis of trumped-up fraud charges that the European Court of Human Rights ruled invalid. His real offenses were helping to lead opposition to Mr. Putin's last reelection, in 2012; producing videos documenting Kremlin criminality, such as the more than $1 billion in property amassed by Prime Minister Dmitry Medvedev; and bringing out tens of thousands of followers in cities across Russia this year to denounce the regime.

Mr. Navalny was credited with 27 percent of the vote when he ran for mayor of Moscow in 2013, and his presentation of his case against Mr. Medvedev had been viewed 25.7 million times on YouTube as of Tuesday. Still, the conventional political wisdom in Moscow holds that Mr. Putin could easily best Mr. Navalny in the presidential election, bolstering both his international and domestic credibility.

He nevertheless prefers to stage a Potemkin vote in which his only challengers will be two perennial candidates, one Communist and one ultra- ­nationalist, and Ksenia Sobchak, a 36-year-old celebrity who has called the election "a high-budget show." Mr. Navalny has now called for a boycott, which means that the Kremlin's reported goal of a 70 percent turnout may be impossible to reach, barring fraud. In one recent poll, only 58 percent said they would vote.

What could explain Mr. Putin's seemingly self- ­defeating tactics? Some analysts argue that the authoritarian regime he has constructed requires not a credible democratic victory but a crushing show of strength. The message must be that there is no alternative. That is particularly true at a time when the regime is failing to deliver the rising living standards it once offered Russians in exchange for their passivity. After two years of recession brought on by falling oil prices and Western sanctions, the economy will grow this year by less than 2 percent.

Mr. Putin now seeks popular favor with nationalist adventurism, such as the invasion of Ukraine; the election is scheduled for the anniversary of the Crimea annexation. But that, too, may be reaching a dead end; Mr. Putin's attempts to broker favorable settlements to interventions in eastern Ukraine and Syria have been floundering. In short, it may be that Mr. Putin has more reason to fear Mr. Navalny than the poll numbers suggest.

Even as he outlaws political competition in Russia, Mr. Putin continues to oversee attempts to undermine and tilt elections in the West. For him, democratic contests are a vulnerability, to be avoided at home and exploited abroad. In that sense, Western governments and Russia's democrats have a common cause in countering Mr. Putin. What both lack is an effective strategy.