Volodymyr Zelenskiy asked his most senior military commander, Valerii Zaluzhnyi, to step down on Monday but the popular general refused, triggering speculation that he will be dismissed instead. Tensions between the two have been simmering for weeks amid the failure of Ukraine’s summer counter-offensive but the suggestion that Zaluzhnyi could be forced out nevertheless came as a shock to many. Oleksii Goncharenko, a Ukrainian opposition MP and ally of the general, told the Guardian that he understood that “yesterday the president asked Zaluzhnyi to resign but he declined to do so”. He blamed personality clashes for the conflict. “Personally I think this is a bad idea. There are not fundamental issues between them but Zelenskiy’s office has been concerned that Zaluzhnyi has been making political not military statements,” Goncharenko said. Expectations that Zaluzhnyi could be forced out imminently surfaced on social media on Monday afternoon. A couple of hours later, the defence ministry responded curtly: “Dear journalists, we immediately answer everyone: No, this is not true,” assuming that everybody reading understood what was being referred to. It is not clear that the matter will end there. Goncharenko said Zelenskiy could dismiss Zaluzhnyi and replace him – a process that requires the support of the defence minister – after assessing the public and international reaction. The most likely replacement would be Kyrylo Budanov, the head of Ukraine’s military intelligence, responsible for covert operations against Moscow. Budanov was touted earlier this year as a replacement for Oleksii Reznikov as defence minister, in another protracted dismissal saga that began with similar bouts of speculation. It is not clear what an alternative military strategy would look like given Russia’s entrenched frontline positions, while Ukraine’s most urgent crisis is not the battlefield but persuading Congress to approve a $61bn military aid package that would secure a year or more’s weapons supply from the US. Democrats on Tuesday accused Republicans of being on the brink of deliberately collapsing a deal linking aid to Ukraine to a tightening of immigration policy at the US’s southern border in order to help Donald Trump’s election campaign. The French president, Emmanuel Macron, meanwhile, urged European leaders to accelerate aid to Ukraine in a speech to Swedish military academy, saying the “costs … of a Russian victory are too high for all of us”. He warned: “There is no more security framework and architecture on our continent if there is a Russian victory.” A Ukrainian counteroffensive that began in June has failed to break through Russian lines amid criticism the attack was spread across too many axes – but the real dispute between the president and his top general appear to be political. The Ukrainian general is the most popular figure in the country other than the president and his high standing has irritated Zelenskiy’s office, particularly as the politician has been considering whether to hold fresh elections, currently suspended under martial law. In a rare interview, Zaluzhnyi told the Economist at the beginning of November that he believed the war was at a stalemate and called for fresh help from the west, but a few days later Zelenskiy dismissed the downbeat assessment. “Everyone gets tired, no matter their status. And we have different opinions. But it’s not a stalemate,” Zelenskiy said at the time, added that newly arriving western F-16 fighter jets could yet lead to a breakthrough in 2024. Speculation has also swirled in Ukrainian media for months that Zaluzhnyi would be the only viable challenger to Zelenskiy for the presidency if fresh elections were to be called while the war continues and the general were to run. Although Zaluzhnyi has never publicly said he would enter politics, informal Facebook posts showing photos of him with his wife were interpreted in Bankova – Ukraine’s equivalent of Downing Street – as a signal of intent. In November, Zelenskiy warned generals against entering politics in an interview with the Sun. He said it would be a “huge mistake” if commanders “manage war keeping in mind that tomorrow you will do politics or elections”. Addressing the military chief directly, he added: “With all the respect to Gen Zaluzhny and to all the commanders who are on the battlefield, there is an absolute understanding of the hierarchy,” in which the president was at the top. In December, leaked polling seen by the Kyiv Independent suggested that Zaluzhnyi was Zelenskiy’s leading challenger and that the incumbent would only narrowly beat him, by two points in a runoff. At the time, the president’s office denied it had heard of the poll, although there were rumours it had been commissioned by them. Orysia Lutsevych, a Ukraine expert with the Chatham House thinktank, said she believed the leaks about Zaluzhnyi’s dismissal were designed to test public opinion. “In view of Russia’s own attempts to destabilise Ukrainian unity from inside, this kind of attack on Zaluzhnyi plays into the enemy’s hands.”