Tymoshenko was sentenced to seven years in jail last month on charges of abuse of office in a trial the U.S. and the European Union have condemned as politically motivated. She was found guilty of violating legal procedures while negotiating a natural gas import contract with Russia in 2009.
Legislators voted Friday to put off the debate on a draft law that could turn Tymoshenko's crime into a milder economic misdemeanor and allow her release.
Tymoshenko says she's innocent and accuses her rival President Viktor Yanukovych of ordering her imprisonment to bar her from parliamentary elections next year. Her conviction has threatened to derail Ukraine's integration with the EU.