Ukrainian President Volodymyr Zelenskiy, in an interview broadcast on Sunday, said he was considering a "reset" to replace several senior officials.
Speculation has gripped Ukraine for weeks over suggestions that the president was about to dismiss the highly popular commander, Valeriy Zaluzhnyi. The two have been at odds over the conduct of the nearly two-year-old Russian invasion of Ukraine.
But Zelenskiy said any changes went beyond replacing a single person to harness efforts to oust Russian troops.
"When I speak of turnover, I have in mind something serious that does not concern a single person, but the direction of the country's leadership," Zelenskyi told Italian state RAI television when asked about Zaluzhnyi.
His comments were voiced over in Italian.
"It is a question of the people who are to lead Ukraine. A reset is necessary, I am talking about a replacement of a number of state leaders, not only in the army sector.
"I am reflecting on this replacement. Is a question for the entire leadership of the country."
To win the war, Zelenskiy said, "We must all push in the same direction, we cannot be discouraged, we must have the right and positive energy, negativity must be left at home. We can't take on giving-up attitudes."
Differences have come to the fore since a Ukrainian counteroffensive launched last year made only limited gains against Russian forces well dug in along the 1,000-km front line in Ukraine's south and east.
In an essay for the Economist last November, Zaluzhnyi said the war had entered a new phase of attrition. That drew a rebuke from the president.
Last week, as speculation over his dismissal intensified, he set out his case in a commentary for broadcaster CNN for new electronic means of warfare.
He also said some Ukrainian institutions were keeping the country from achieving its objectives, including efforts to build an effective fighting force to match Russian numerical superiority through "unpopular measures" like mass moblisation.
Zaluzhnyi has earned the admiration of Ukrainians for overseeing operations to repel Russian forces advancing on Kyiv at the outset of the war and subsequent advances that recaptured large swathes of territory in the south and northeast.
On two occasions in the past week, Ukrainian media issued a torrent of reports that Zaluzhnyi's dismissal was imminent. In at least one instance, the president's spokesperson denied the commander had been replaced.
Questions were also raised over whether Zaluzhnyi had been offered an alternative job, like an ambassadorship, and who might replace him.
Two leading possible candidates were Oleksandr Syrskyi, commander of land forces, and Kyrylo Budanov, head of the Ukrainian defence ministry's intelligence directorate.