Former Prime Minister Tymoshenko was sentenced to seven years in prison in 2011 on charges she abused her office in negotiating a 2009 natural gas deal with Russian energy company Gazprom. Her supporters say the charges against her were politically motivated.
Tymoshenko has suffered various health complications while in prison. She staged a hunger strike last year.
Volodymyr Oliynyk, a member of the ruling Party of Regions, said his slate "will not vote" on the legislation Thursday because lawmakers were revisiting the measure at the working group level, the National News Agency of Ukraine reports.
If passed, the legislation would allow Tymoshenko to travel to Germany for medical treatment.
The European Union said cases against Tymoshenko and her supporters are among the issues potentially standing in the way of an association agreement on the agenda for a late November summit in Lithuania.
Opposition leaders in Kiev said they're ready for "any compromise" that would settle the issue before the Lithuanian summit, the report said.