Voting ended on Saturday in the Czech Republic's two-day municipal and Senate elections, tainted by allegations of vote buying in some northern Czech towns, DPA reported.
Police are investigating several cases in which mostly Roma, also known as Gypsies, were promised cash in exchange for voting for a specific party.
In one case, described by the Czech news agency CTK, dozens of voters gathered in a bar where they were instructed by unknown men to vote for a local party if they wanted to collect a reward. They were then driven to a polling station in a minibus.
Statisticians are expected to compile complete unofficial results by Sunday morning, with the announcement of official results by the State Electoral Commission planned for Tuesday.
The outcome will show whether Czechs continue to prefer newly founded protest parties and whether they will punish Prime Minister Petr Necas' three-party, centre-right government for planned austerity measures.
Good results for the leftist opposition could threaten the government's unity and force the cabinet to soften its planned spending cuts and public finance reforms.
If the Social Democrats win 12 of the 27 seats up for election in the parliament's upper house, the Senate, their new majority could cause the cabinet significant headaches by returning austerity and reform legislation to the lower house.
In one of the most closely watched races, Necas' centre-right Civic Democratic Party may lose the municipal election in the capital Prague for the first time in nearly 20 years to a coalition partner, the new conservative party TOP 09.
The Senate poll, in which voters were selecting one third of the country's 81 senators, will proceed to the second round next week in districts where neither candidate wins more than a half of the vote.