Czech Prime Minister Petr Necas was facing the collapse of his shaky centre-right minority coalition Saturday over a massive corruption scandal in which his top aide was indicted for bribery.
Leftist rival President Milos Zeman said Saturday it was "rather clear" that Necas must step down, while junior coalition partners in the premier's three-party government questioned his integrity.
The coalition government has so far survived eight confidence votes since it took power in July 2010. But it will face another test next week as Zeman's allies, the opposition Social Democrats, have put forward a no-confidence motion, likely on Tuesday.
The unprecedented graft scandal rocking Prague erupted when police swooped overnight Wednesday and Thursday on the cabinet office, defence ministry, villas and a bank.
Jana Nagyova -- Necas's chief of staff and alleged lover -- was on Friday charged with complicity in the "abuse of power and with bribery". She will remain in police custody pending trial.
Seven other people -- including military intelligence heads and former lawmakers -- have also been indicted for corruption among other alleged crimes.
The 48-year-old Nagyova was charged with bribery after allegedly promising three former lawmakers from Necas's party lucrative jobs in state-run companies on condition they quit the parliament.
But during the corruption probe, police also uncovered instances in which they say Nagyova had abused her power, by asking the head of Czech head of military intelligence to tail the prime minister's wife Radka, 47, and two other people.
Necas announced this week he was getting divorced from his wife after more than 25 years, sparking media speculation that Nagyova was his lover.
Ironically, the premier made a high-profile anti-corruption drive a centrepiece of his coalition.
So far Necas, a 48-year-old physicist, has refused to quit and has expressed confidence that his top aide was innocent.
But the scandal has led the junior coalition parties in Necas's minority government, the right-wing TOP 09 and centrist LIDEM, to question his integrity.
"The prime minister hasn't made things clear, we don't know if he was aware of the acts (by aide Nagyova), which would be a scandal," said LIDEM head Karolina Peake.
Analysts in Prague have pointed to the likelihood of a snap election, which according to fresh polls would usher the leftwing into power. The next regularly scheduled election is due in May 2014.
According to analyst Vladimira Dvorakova at the University of Economics in Prague, "snap elections will be held because I can't imagine this going on for a year after the current situation".
An EU member since 2004, the ex-communist Czech Republic has been plagued by corruption since it emerged as an independent state after its 1993 split with Slovakia.
Corruption watchdog Transparency International in 2012 ranked the Czech Republic as worse than Costa Rica and Rwanda in terms of the prevalence of graft in its "Corruption Perceptions Index".