The Fatherland Party, a group led by jailed former Prime Minister Yulia Tymoshenko, joined a coalition of opposition parties calling for early elections. The United Opposition slate said it would "denounce the next Parliament as powerless," reports Radio Free Europe/Radio Liberty.
Yuriy Kluchkovsky, identified by RFE/RL as an opposition deputy, said robbing the Parliament of its mandatory 300-member quorum was a difficult political move.
"Achieving this would be quite difficult," he said. "Everybody on the party list, right down to the last person on this list, must personally refuse to take up his or her seat."
Following the Oct. 28 election, the head of the observer mission from the Organization for Security and Cooperation in Europe said "democratic progress appears to have reversed in Ukraine."
Tymoshenko, jailed after a conviction on corruption charges stemming from a 2009 gas deal with Russia, said she was staging a hunger strike to protest the election.
RFE/RL reports the Party of Regions, led by Ukrainian President Victor Yanukovych, has secured 30 percent of the vote in preliminary results for the 450-seat legislative assembly. Tymoshenko's party took second place.