On a recent Sunday the parking lot outside Mega, a giant shopping mall on the outskirts of Moscow, was packed with the cars of Christmas shoppers in their annual commercial frenzy. Towering above them, and looking somewhat out of place, were 14 large trucks decorated with protest banners.

"We want to feed our families, not oligarchs," "Allow us to work," and "Legitimized robbery," the banners read. The truckers, hailing from Russia's northwest, had set up camp three weeks earlier. They're protesting a new road tax that they say benefits a family close to President Vladimir Putin. On the other side of the city there's another protest, run by drivers from the southeast, and across the country there are a dozen more sites of trucker dissent.

The truckers have threatened to block access roads to Moscow, but so far they've been too few and too cautious to do so. Yet the authorities are reluctant to crush the protests in the same way they did when middle-class urbanites staged rallies in 2012. Truck drivers, like other blue-collar workers, are ostensibly Putin's people, having fed the increase in his approval ratings after he annexed Crimea. Commercial truckers are loosely organized around the radio frequencies they use. With no real trade union, it's hard for government authorities to handicap just what kind of threat they face.

"For the moment, we are just making our presence known," said one protest coordinator, Andrey Bazhutin. "We can rally several hundred thousand trucks if necessary."

The one-two punch of plummeting oil prices and Western sanctions has left a gaping a hole in Russia's budget, covered in part by a rainy-day fund of accumulated revenue from when energy prices were higher. Finance Minister Anton Siluanov warned in October that the money will be exhausted by the end of 2016, likely triggering spending cuts and higher taxes unless oil prices rebound.

One of the protesters, Sergey Gorodeshenin, said he was earning around 65,000 rubles a month last year, or $912, but falling demand cut his monthly pay to about $420. Gorodeshenin, from Vologda, about 250 miles north of Moscow, said he spends half of his earnings to feed his wife and two children. The rest is barely enough to make loan payments and keep his two large vans running. The truck drivers say the new tax, collected through the Platon payment system, will strip them of what little income they have left. Platon is operated by a company co-owned by Igor Rotenberg, whose father attended judo classes with Putin in the 1960s.

Gorodeshenin said if he's forced to pay the new tax, "my children will be left with nothing at all."