Czechs began voting on Friday in a two-day snap election that will likely see them hand power to the left-wing opposition in frustration over years of graft and austerity.
Polling stations opened at 2:00 pm local time (1200 GMT) to end months of political turmoil set off by a spy and bribery scandal that brought down the centre-right government of Petr Necas.
Voters already made a sharp left turn in January, electing ex-Communist Milos Zeman as president after a decade under the right-wing and eurosceptic Vaclav Klaus.
The Social Democrats (CSSD) topped pre-vote opinion polls but whether they will team up with the Communists or a breakout populist party remains unknown.
"No clear majority coalition is in the cards," Jan Outly, a political analyst at the Metropolitan University in Prague, told AFP.
Coalition governments lacking comfortable majorities are the norm on the fragmented Czech political scene. Smaller parties or independent MPs must often be wooed for support.
The latest opinion survey gave 26 percent of the vote to the Social Democrats, 18 percent to the Communists and 16.5 percent to the populist party ANO led by billionaire Andrej Babis.
The Slovak-born farming tycoon -- who sells everything from foodstuffs to fertiliser -- has capitalised on the blow dealt to the right by the June bribery scandal.
Social Democrat leader Bohuslav Sobotka says his party could go it alone in a minority government in the 200-seat parliament, relying on the Communists' tacit support.
But many Czechs are incensed by the prospect of the far-left becoming a powerbroker for the first time since the Velvet Revolution brought down totalitarianism over two decades ago.
Anti-communists hoisted a massive banner of Russian President Vladimir Putin dressed as Soviet dictator Joseph Stalin atop a central Prague hill on Friday.
Behind it stands the "Time Machine", a huge pendulum installed in 1991 -- two years after communism fell -- where a massive statue of Stalin once stood.
Czech artist David Cerny also gave Zeman the finger -- a huge purple one floating along the river before the presidential castle -- in protest against his soft spot for the Communists.
And Czech rockers played gigs in Prague and Brno called "Nikagda nezabudem" in Russian or "We'll never forget".
But others, hurting from years of austerity and a record 18-month recession that ended in the second quarter, welcome a swing to the left.
"I'm voting for the Social Democrats because we can't go on like this, the country is so terribly plundered that we need change," Radka Linhartova, a 48-year-old Prague nurse, told AFP.
"Even if the devil himself took over, it would be better than what we've had up to now."
Like the Social Democrats, the Communists have vowed generous welfare programmes, but they also want the Czech Republic to leave NATO.
Sobotka has so far ruled out teaming up with Babis.
Analysts say his ANO party -- meaning "yes" and an acronym for Action for Alienated Citizens -- is a force to be reckoned with but point out risks.
"It's hard to figure out (ANO's policy stance) and so it's a risky coalition partner. I think the Social Democrats will look at all other possible coalitions," Outly said.
Set up in 2011, ANO has gained ground by wooing disillusioned voters away from parties across the spectrum with promises of fighting graft.
"I like (Babis) because he's sharp and doesn't let anyone dictate things to him," said Jitka Cechlovska, a Prague waitress in her thirties.
A legacy of four decades of totalitarian rule and corruption has plagued the EU member of 10.5 million people since its 1993 split with Slovakia.
Transparency International ranks the Czech Republic as more corrupt than Rwanda and 94 percent of Czechs believe graft is "widespread in government", according to a poll released by the Gallup Institute last week.
Polling stations close at 1200 GMT on Saturday.