The choice of venue and the occasion highlighted Mr. Putin’s support base — workers of Russia’s big industrial enterprises. During the street protests in Moscow in 2011-12, workers at a similar plant in central Russia offered Mr. Putin their help in dispersing anti-Kremlin protesters.

Mr. Putin is expected to cruise to re-election, not least because of his popularity and the lack of serious challengers. In fact, the main concern in the Kremlin now, according to political analysts of all stripes, is that the lackluster slate of candidates could drive turnout to historic lows and deprive Mr. Putin of a resounding mandate.

But there is no denying Mr. Putin’s popularity. The 2014 Winter Olympics in Sochi, Russia, dominated by Russia with 33 medals, also fueled his ratings. The scandal over state-backed doping, which saw Russia barred from the 2018 Winter Games, only seems to have bolstered his standing, as it fits into his narrative of Russia as a besieged fortress surrounded by enemies on all fronts.

Domestically, Russians experienced instability and poverty after the 1991 collapse of the Soviet Union. After assuming the presidency in 2000, Mr. Putin brought stability and an extended period of prosperity, with Russians gaining more household income in the first eight years of his term — mostly because of rising prices for energy, the country’s main commodity — than during any other period in their recent history.

That has gone into reverse in recent years, since the 2014 collapse in the price of oil and the ruble. But Russians have yet to blame Mr. Putin personally.

If anything, his popularity has been inching upward since the summer. A poll by the Levada Center in September showed 52 percent of voters supported him overall and 64 percent among those who said they would vote. The poll was based on 1,600 people questioned on Sept. 15 to 19, the center said.

His strongest rival, Aleksei Navalny, an anticorruption crusader and opposition politician who organized several large national protests this year, has been barred from running because of a series of criminal cases that he and rights advocates call politically motivated. Yet, even if he were allowed to run, it is doubtful that he would be popular enough to threaten Mr. Putin.