The Social Democrats were leading in the Czech Republic's early elections with 25 percent of ballots counted on Saturday as voters angered by years of right-wing graft and austerity veered left, official results showed.
The Social Democrats scored 22.13 percent, ahead of the surprise populist newcomer ANO movement of billionaire Andrej Babis with 18.61 percent and the Communists with 17.08 percent vying for second place.
The right-wing TOP 09 and ODS were also set to surpass the five percent threshold needed to enter parliament with 9.4 and 6.73-percent support, respectively.
Dawn of Direct Democracy, a populist party led by Japanese-born businessman Tomio Okamura, scored 7.53 percent. Christian Democrats scored 6.79 percent.
The ballot caps months of political turmoil set off by a spy and bribery scandal that brought down the centre-right government of Petr Necas in June.
Voters already swung left in January, electing former Communist Milos Zeman as president after a decade under the right-wing and eurosceptic Vaclav Klaus.
Despite an apparent Social Democrat victory, it was unclear Saturday whether they would team up with the Communists or ANO.