Pressure is mounting on Ukrainian President Volodymyr Zelenskyy to take stronger action to show accountability in the face of a corruption scandal presenting the greatest threat to his government since Russia's full-scale invasion.

Last week, Zelenskyy dismissed two top officials and imposed sanctions on close associates after government investigators revealed that $100 million had been embezzled from the energy sector through kickbacks paid by contractors.

But that hasn't quieted the political storm. After more than three years of war in which Ukrainians face regular power outages as a result of Russia's fierce bombardment, allegations of corruption in the energy sector aren't sitting well with the public.

Calls are growing for Zelenskyy to remove his longtime chief of staff, Andrii Yermak, considered by many to be Ukraine’s de facto vice president.

Neither Zelenskyy nor Yermak have been accused of any wrongdoing by those leading the corruption investigation.

Yet Zelenskyy’s political opponents — as well as allies worried the scandal could weaken their parliamentary governing coalition — say more senior leaders need to be held accountable to restore public trust.

Zelenskyy’s term officially ended in May 2024, but he has continued to govern without elections, saying they cannot be held while Russia is occupying a fifth of the country.

His critics say it's also important to bolster credibility with Ukraine's Western allies, whose support is vital to the war effort and in eventually negotiating an end to the conflict.

Ukraine has been plagued by corruption since gaining independence, and Zelenskyy was elected on a mandate to eliminate graft.

Two officials in Zelenskyy's office say the president has not made any decision to dismiss Yermak.

The officials spoke on condition of anonymity because they were not authorized to brief journalists.

The investigation conducted by Ukraine's anti-corruption watchdogs implicated high-ranking officials with pressuring contractors to pay up to 15% kickbacks in exchange for construction business with Ukraine’s state-owned nuclear energy company, Energoatom.

The investigation involved over 1,000 hours of wiretaps of individuals using code names and cryptic language to discuss the scheme.

In some conversations, references were made to a powerful figure operating under the alias “Ali Baba,” though this person's identity has not been made public, if it is even known.

After the scheme was made public, Ukraine’s parliament approved Zelenskyy’s dismissal of the energy and justice ministers.

His office imposed sanctions on close associates who were implicated, including Tymur Mindich, a co-owner of Zelenskyy’s media production company.

The scandal landed just as Russian airstrikes had left millions of Ukrainians without power, which only intensified the furor.

Earlier this year, Zelenskyy faced criticism for trying to weaken the watchdog agencies leading the investigation.

Zelenskyy's political opponents say it is hard to believe that such a huge corruption scheme could have taken place without the knowledge of Yermak — the presidential adviser who has towered over Ukrainian politics for six years — though they have not provided any evidence to support the allegation.

Yermak has not publicly addressed the calls for his resignation.

However, he has apparently sought to bolster his support within the government.

He sought to arrange a meeting with Ukraine’s popular former army chief, Valerii Zaluzhnyi, who is currently Ukraine's ambassador to the United Kingdom, according to an official close to Zaluzhnyi who spoke on condition of anonymity because they were not authorized to discuss the matter publicly.

The request for a meeting was denied, the official said.

Yermak's spokesperson did not respond to request for comment.

AP video by Vasilisa Stepanenko