A high court in Kiev deliberated the conviction of Tymoshenko, a former prime minister accused of abusing her authority in a 2009 gas deal with Russia's Gazprom. The Interfax news agency reports thousands of people gathered Tuesday in Kiev to call for her immediate release.
Tymoshenko lost an election campaign to President Viktor Yanukovych in 2010. Her supporters, including U.S. and European leaders, have said they believe charges against her are politically motivated.
Oleksandr Turchynov, first deputy leader of Tymoshenko's opposition party, said it's unlikely foreign influence would sway the courts under the current administration.
"It will be possible to release prisoners, release Tymoshenko and release Ukraine only by winning these elections," he was quoted by Interfax as saying.
Parliamentary elections in Ukraine are scheduled for October.
Tymoshenko in April staged a brief hunger strike to protest her prison conditions.