Yevgeny V. Prigozhin quietly profited from his personal ties to President Vladimir V. Putin of Russia, winning lucrative catering and construction contracts with the Russian government while building a mercenary force known as Wagner.
After throwing his fighters into Ukraine, their ranks swelled with prisoner recruits, Mr. Prigozhin emerged as a public power player, using social media to turn tough talk and brutality into his personal brand.
In a scorching video posted Friday on social media, Mr. Prigozhin threatened to pull his fighters next week out of Bakhmut, the embattled city where he has thrown thousands of convicts into the maw of Ukraine’s defenses, taking extraordinary casualties in a stubborn effort to wear down the other side.
Citing a lack of ammunition, Mr. Prigozhin delivered the ultimatum after walking among rows of bodies that he claimed were Wagner fighters killed in the battle for Bakhmut. He called out Russia’s defense minister, Sergei K. Shoigu, and Gen. Valery V. Gerasimov, the chief of the military general staff, as responsible for their deaths.
Mr. Prigozhin, a businessman known as “Putin’s chef” because of his catering contracts with the Kremlin and Russian military, has complained about ammunition shortages and threatened to pull out of the city before, but he has not previously given a date. It was unclear if he would follow through this time.
Spewing vulgarities, disregarding the law and displaying loyalty to no one but Mr. Putin, Mr. Prigozhin has become a symbol of wartime Russia: ruthless, shameless and lawless. Mr. Prigozhin’s attention seeking is particularly striking because he acknowledged only last fall that he had founded Wagner.
But there are obstacles to Mr. Prigozhin’s rise. He is facing public blowback in St. Petersburg, his home base, as he tries to exert control over the politics of the city, Russia’s second largest. And he is dogged by open questions and criticism in Moscow, where analysts doubt that his recruitment of prisoners and endorsement of extrajudicial executions have broad appeal.
Mr. Prigozhin jumped into the fray by expanding Wagner’s presence in Ukraine after the Kremlin’s initial attempt to seize Kyiv, the capital, failed early last year. The “private military company” was at that point largely active in Syria and Africa, where it operated both on behalf of the Russian government and in the service of Mr. Prigozhin’s own business interests.