There will be no quick finish to Russia’s military campaign to subdue Ukraine, according to a renegade former Ukrainian parliamentarian who has been sanctioned by the European Union after becoming a separatist leader. 

In a lengthy interview with the Russian newspaper Komsomolskaya Pravda, the former people’s deputy of Ukraine, Oleg Tsaryov, agreed with his Russian interlocutor that “we won’t finish it by autumn.” The widely reviled politician added that “then the Ukrainians will be pumped up, they will mobilize twice as many soldiers and tell themselves that they have stopped the military colossus of the Russian Federation.”

Mr. Tsaryov, who reportedly has close ties with Vladimir Putin, was the subject of a somewhat unsettling article published in the Financial Times 10 days before Russia invaded Ukraine. That article, headlined, “US shares fresh claims of Moscow coup plot for Ukraine,” said his name as Mr. Putin’s possible choice to lead regime change in Ukraine “in the event of a Russian invasion” came from U.S. intelligence, which made it available to the Five Eyes intelligence alliance made up of America, Britain, Australia, Canada, and New Zealand. 

A former senior Western intelligence official said in the article that Mr. Tsaryov “might be a useful marionette until a long-term candidate can be groomed.”

While his multiple claims to the Russian newspaper are obviously completely biased in the direction of Moscow, they may not all be as spurious as they might at first seem. “A marginal minority is fighting against us” in Ukraine, he said.

“And the country is big. The Russian Federation wants to take control in a very short time of a country with a population somewhere between 20 percent to 30 percent of its own. And all this within the framework of a special operation. Here it is necessary to strain the whole country,” Mr. Tsaryov said. 

By that he meant that Russia will need to make a bigger effort to take Ukraine, and he offered up various suggestions, from encouraging more Russian volunteers to join the fight to reassessing what he said was the Kremlin’s instructions to Russian soldiers not to touch Ukrainian flags — and ostensibly to replace them with Russian ones.

The rogue Ukrainian may have friends in high places — which is to say the Kremlin — but not in too many other places. He was sanctioned by the European Union in May 2014 for calling for the creation of the Federal State of Novorossiya. The Financial Times described Mr. Tsaryov as a native of Dnipro in eastern Ukraine who served in the pro-Moscow Party of Regions led by Viktor Yanukovych, who fled to Russia in 2014 following a pro-Western revolution. 

After Russia’s annexation of Crimea the same year and the beginning of a Moscow-backed separatist conflict in Ukraine’s eastern Donbas region, Mr. Tsaryov ran for president on a pro-Russian ticket that was so unpopular, according to the FT article, that he was chased out of a Kiev TV studio and beaten up by an angry mob.

Yet his being given a prominent interview in Komsomolskaya Pravda, one of Russia’s most popular newspapers — its slavish following of the Kremlin’s line notwithstanding — could be harbinger of a page in Mr. Putin’s playbook. In an apparent refutation of what was suggested in the Financial Times article, Mr. Tsaryov said that the majority of what he termed “voters” are against a separate state of Ukraine and want Mr. Putin to be president, and that he is part of that majority.

Asked about what could happen to Ukraine after what Moscow is still calling a “special operation,” Mr. Tsaryov said darkly, “I have an understanding of this. I will not reveal the scenario, but I can only say that the Ukrainians will choose their own fate.”