His private army is pushing hard to give Russia a battlefield win in Ukraine, but mounting evidence suggests the Kremlin has moved to curb what it sees as the excessive political clout of Yevgeny Prigozhin, founder of Russia's Wagner mercenary group.
Prigozhin, a 61-year-old ex-convict, has grabbed headlines in recent months over his bloody role in Ukraine and is sometimes portrayed in the West as a real-life James Bond villain.
Shaven-headed and fond of coarse language, he has made a splash in Russian-language media too where he has revelled in being sanctioned by the West, publicly insulted Russia's top military brass, tried to parlay battlefield success into Kremlin favour, and detailed his recruitment of tens of thousands of convicts for his private army.
His profile became so prominent that allies and analysts began speculating he was angling for an official job or career in politics.
There is growing evidence now though that the Kremlin has moved to nip such speculation in the bud, ordering Prigozhin to halt his public criticism of the defence ministry while advising state media to stop mentioning him or Wagner by name.
Prigozhin confirmed last week he had also been stripped of the right to recruit convicts from prisons - a key pillar of his nascent political influence and one which has helped his forces make small but steady gains in eastern Ukraine where they appear to be inching closer to capturing the city of Bakhmut.
Olga Romanova, director of a prisoner rights group, said the Ministry of Defence had taken over convict recruitment earlier this year. The ministry has not confirmed that.
"The position of the (Kremlin) political bloc is not to let him into politics. They are a little afraid of him and find him an inconvenient person," Sergei Markov, a former Kremlin adviser who remains close to the authorities, told Reuters.
Political player?
Tatiana Stanovaya, a veteran Kremlin scholar, wrote in a paper for the Carnegie Endowment for International Peace that, while Prigozhin's downfall did not appear imminent, his ties with the presidential administration were starting to crack.
"The domestic policy overseers don't like his political demagogy, his attacks on official institutions, or his attempts to troll Putin's staff by threatening to form a political party, which would be a headache for everyone in the Kremlin," she wrote.
"He hasn't just become a public figure; he is visibly transforming into a full-fledged politician with his own views."
According to Markov, the Kremlin has got a promise from Prigozhin that he would not create his own political movement or join a parliamentary party unless asked to do so by the Kremlin.
"(The message) is we will give you military resources, but do not get involved in politics for now," said Markov.
Prigozhin told a Russian interviewer on Friday that he had "zero" political ambitions.
Markov, who described Prigozhin as extremely confrontational, said he believed Putin had told Prigozhin to halt public criticism of the top brass at a St Petersburg meeting around Jan. 14.
Markov said he did not know full details of who said what at the meeting and Reuters was not able to confirm the accuracy of his assertion.
Prigozhin has since moderated his criticism and made a point on Friday in a rare interview of looking into the camera to say he wasn't criticising anyone.
The St Petersburg meeting, which did not appear on the Kremlin website, was confirmed by at least one other attendee who posted about it on social media. The Kremlin says it does not comment on private meetings.
The Kremlin did not immediately reply to a request for comment about whether and why it had reined in Prigozhin, but on Saturday, Grey Zone, an influential social media channel associated with Wagner, published what looked like a leaked guidance document for state media from the Kremlin.
It advised recipients to stop mentioning Prigozhin or Wagner and suggested generic phrases to describe his forces instead.
Reuters could not verify the document and state media are not allowed to share such guidance notes.
'His star dimmed'
Prigozhin, in comments on Monday, said it looked like Russian media mentions of Wagner had fallen recently, something he blamed on unnamed "losers" trying to damage his group.
Markov, who has written about Prigozhin a lot in a mostly positive light, said he was among those to have been requested not to promote the mercenary leader.
"They underlined that 'we don't ban you but it's better not to do it'," he said.
Dmitri Alperovitch, the Russian-born chairman of US think-tank Silverado Policy Accelerator, said he felt Prigozhin's room for manoeuvre was shrinking.
"Prigozhin's star has dimmed. He had overreached in his criticism of the military and other elites," Alperovitch wrote on Twitter. "Now his wings are getting clipped."
After years of denials, Prigozhin stepped out of the shadows in September to admit he had founded Wagner in 2014.
By then, Russia's invasion of Ukraine, something Moscow calls a special military operation, had gone badly wrong for the top brass, with a chaotic retreat from Kyiv followed by a rout in the north-eastern Kharkiv region, and an impending forced retreat from the southern city of Kherson.
The wealthy catering tycoon quickly put himself at the heart of a frenzied public relations campaign and, through social media, state TV and feature films, promoted his private army as an elite fighting force that could work military alchemy.
He cast himself as a ruthlessly efficient patriotic operator and Russia's top brass as incompetent and out-of-touch.
Prigozhin, whose mercenaries are active in Africa and the Middle East, suggested last week that he and his men could one day disappear as fast as they appeared, something his many enemies may doubt.
"When we are no longer needed, we will pack up and go back to Africa," he said.