Opinion polls of voters found that Prime Minister Victor Ponta's ruling Social-Liberal Union was favored at about 57 percent, Voice of America reported.
President Traian Basecu's Right Romania Alliance polled at about 20 percent. The report did not give the details of the opinion polls or their margins of error.
Ponta's government attempted to impeach Basecu in July and accused the president of exceeding his authority, undermining the rule of law and meddling in government affairs. Basecu, however beat the referendum seeking his impeachment, RIA Novosti reported.
The Organization for Security and Cooperation in Europe is monitoring Sunday's vote. Results are expected to be announced after polls close at 9 p.m.