MOSCOW – A campaign of insinuation and insult has targeted Prime Minister Dmitry Medvedev, and in a country where all power flows from the top downward, his boss, President Vladimir Putin, has done nothing all winter to stop it.

Medvedev’s failings get an airing in the press, and nasty anonymous video documentaries accuse him of all sorts of treachery. Slights and humiliations are visited on him by the Kremlin, seat of the presidential apparatus. Governors go around him. Bureaucrats ignore him. Putin, in public, takes little care to hide his disdain.

Medvedev responds by repeatedly trying to demonstrate his loyalty to Putin, which draws ridicule from politicians and pundits alike. As a consequence, the Cabinet of ministers that Medvedev chairs is barely able to function.

The Kremlin could halt the abuse any time it wanted to, said Lilia Shevtsova of the Moscow Carnegie Center. But Putin intends to send a clear message to the rest of his circle that Medvedev is irrevocably out of favor. And it is a symptom of one of Putin’s strongest characteristics, she added: “He enjoys it when other people are being hurt.”

Gleb Pavlovsky, a once-trusted Kremlin insider who was fired in 2011, has a darker view: that Putin has convinced himself that Medvedev betrayed him, has conflated Medvedev with political protesters who in fact oppose both men, and is lashing out in all directions in a fight against demons that only he can see.

This, Pavlovsky said in a recent interview, explains the anti-Americanism, the trials of political foes and the strident denunciations of the liberal elite.

Worse, he said, the mood of distrust is infecting the whole political establishment, ushering in what he called a Russian McCarthyism.

A case in point is the Duma, the lower house of Parliament, where members try to outdo each other in finding new menaces to ban while ignoring the challenges Russia actually faces, he said.

It was not always this way. From 2008 to 2012, Medvedev was president and Putin prime minister. Putin had already served two terms as president, and stepping into the prime ministership was a way to remain in power without violating the constitution. The idea was that they would be a “tandem” in running the country, with Putin in control but Medvedev faithfully carrying out the duties of the presidency.

It worked for a while, said Pavlovsky, a principal architect of the arrangement. His hope, he said, was that it would constitute a transition toward an actual electoral democracy.

But even as Medvedev showed himself to be more tentative and cautious than he had to be, he began talking in 2011 as though he might seek re-election. Communications between the two leaders were bad, and Putin, Pavlovsky said, suddenly sensed betrayal.

That is when he decided to take the presidency back. Medvedev acquiesced but insisted on becoming prime minister, and Putin, perhaps out of misplaced fear that he would become a leader of the opposition, agreed.

But Putin was so wounded by what he believed to be Medvedev’s motives, Pavlovsky said, that he is now suspicious of everybody. This is not only bad politics, he said, but it has left all those close to Putin unsure of where they stand or what will happen.

“The tandem turned out to be destructive for both these politicians — they damaged each other,” Pavlovsky said. “One was traumatized, and the other stopped existing as a political personality.”

Putin could fire Medvedev any time he wants, although he isn’t normally one to let people go.

“He can despise Medvedev, he can walk him around like a lap dog, he can condescend to him — but he cannot just brush him aside,” Shevtsova said. “That would undermine the tightness of the gang.”

More likely, she said, is that the president is preparing Medvedev to be the scapegoat when some crisis comes along that requires one.

Putin may feel that he has to crush Medvedev before the premier can discard him, said Kirill Rogov, an analyst at the Gaidar Institute, or else the prime minister might rise again to challenge him.

Fiona Hill and Clifford Gaddy, both at the Brookings Institution, have just published a book that analyzes Putin’s presidency, and they pointed out at a recent forum that Medvedev, who is 13 years younger than Putin, would have been a law student during the years of the great prodemocracy demonstrations before the Soviet collapse and probably took part in some. Putin, at that time, was a KGB officer in isolated Dresden, East Germany.

So in one sense Putin was right if he believed that the crowds of protesters this past year in Moscow were “Medvedev’s people.” They are his age, largely from his sort of background, and of the same modern sensibility.

Now Putin’s cherished “vertical of power” has been rerouted to bypass Medvedev.

Putin’s 60 percent approval rating would be high in any true democracy, Rogov said, but it is not sufficient in Russia’s “electoral authoritarianism.” Putin’s system depends on there being no alternative — or no promise of one — and a mythology of overwhelming consensus.

Alarmed by the opposition, Rogov said, Putin has moved forcefully to “separate” the liberal urban protesters from the rest of Russian society — embracing traditionalism, nationalism and the church.

“This is much more serious than I thought even a month ago,” he said.

The new mood helps explain the most recent anonymous video attacking Medvedev. It luridly accuses him of treasonably betraying Russia by going along with NATO action in Libya.

Having embarked on this course, Putin cannot turn back, Rogov said.

His problem is that more and more people who have gone along with him up to now will be repelled by the new fundamentalism.

Putin used to be the defender of the status quo, but now he is the agent of change — in a direction that plenty of influential Russians will not care for.

“Putin is becoming a nuisance to the elite,” Shevtsova said. “At some point, he will have to use force and coercion. That is the logic of the reign. But he’s not ready. He’s not Stalin.”