European Council President Charles Michel said he is confident EU leaders will vote Thursday in favor of granting candidate status to Ukraine.
EU leaders gathered in Brussels were also set to discuss the impact of Russia's war in Ukraine on global food security, as well as additional EU economic, military and humanitarian support for Ukraine.
The European Commission recommended EU candidate status for Ukraine and its smaller neighbor, Moldova, last week.
The candidacy status is just the first step toward joining the 27-member group. Ukraine will need to meet political and economic conditions, such as meeting standards on democratic principles. Diplomats say the process could take a decade to complete.
Ukrainian President Volodymyr Zelenskyy said in his nightly video address to the nation that he had spoken to 11 European Union leaders Wednesday about Ukraine's candidacy and would make more calls Thursday. Earlier, he voiced his optimism at joining the EU, saying he believed all 27 EU countries would support Ukraine's candidate status.
Zelenskyy said Russia carried out "massive air and artillery strikes" in eastern Ukraine's Donbas region, adding that Russia's goal is to "destroy the entire Donbas step-by-step."
The Ukrainian leader called for faster arms deliveries to help his forces match up against those from Russia.
Kharkiv region Governor Oleh Synehubov said Wednesday shelling of the residential districts of Kharkiv or other towns in the region had continued unabated.
'There is no letup in the shelling of civilians by the Russian occupiers,' he wrote on the Telegram messaging app. 'This is evidence that we cannot expect the same scenario as in Chernihiv or Kyiv, with Russian forces withdrawing under pressure.'
Ukrainian presidential adviser Oleksiy Arestovych said in a video address that Russian forces were hitting Kharkiv 'with the aim of terrorizing the population' and forcing Ukraine to divert troops, Reuters reported.
Microsoft reported Wednesday that Russian intelligence agencies have conducted multiple efforts to hack the computer networks of Ukraine's allies.
'The cyber aspects of the current war extend far beyond Ukraine and reflect the unique nature of cyberspace,' Microsoft President Brad Smith said in the report.
The Russian embassy in Washington did not immediately respond to a request for comment, Reuters reported. In the past, Moscow has denied conducting foreign cyber espionage missions, saying it 'contradicts the principles of Russian foreign policy.'
Since the conflict began four months ago, Ukrainian entities have been attacked by Russian state-backed hacking groups, Microsoft reported. Researchers found 128 organizations in 42 countries outside Ukraine were also targeted by the same groups in espionage-focused hacks, the report found.
Nearly two-thirds of the cyberespionage targets involved NATO members, researchers found.
Some information came from The Associated Press, Reuters, and Agence France-Presse.