Czech President Milos Zeman is expected to name a technocrat prime minister on Tuesday after an unprecedented corruption scandal toppled the government.
But political leaders said they would oppose the appointment over fears it could give the president too much power, pledging instead to push for early elections.
Zeman, who took office after a landslide victory in the Czech Republic's first direct presidential vote in January, said he would appoint a successor to toppled prime minister Petr Necas at 1300 GMT.
Necas was forced to step down last week after his chief of staff and alleged lover was indicted for abuse of power and bribery amid a massive scandal unheard of even for the graft-prone country.
Local media and analysts have tipped Zeman's aide, 52-year-old Jiri Rusnok, as the frontrunner, but the president himself has said he has four names in mind.
Rusnok, an economist who was finance minister in Zeman's leftist government in 2001-2002, became his economic adviser after he was elected president.
But political leaders have pledged to challenge the appointment which they fear would be used by the president to expand his power.
Tipped to win any early election, the left-wing Social Democrats are already urging an early vote, along with the far-left Communists and right-wing Civic Democrats and TOP 09 parties.
Together, they have 171 votes in the 200-seat parliament, far more than the 120 votes required to dissolve it under the constitution.
According to the constitution, snap elections must be held within 60 days after dissolution of parliament.
However, Zeman can still block early polls, as it is ultimately up to the president to set a date for the elections.
"He may put off the decision under various pretexts," said political analyst Jiri Pehe.
With an apolitical technocrat administration, Zeman "will gain control over the government, at least temporarily," added the analyst.
"He will be able to push through some of his plans that he wouldn't be able to enforce with a political government," Pehe told AFP.
Among these plans is the construction of two new units at the Temelin nuclear power station, a contract worth an estimated 200 to 300 billion koruna (8 to 12 billion euros, $10 to 15 billion). The contract winner is due to be announced in autumn.
In the wake of the corruption scandal, 55 percent of Czechs want a snap election. The next regularly scheduled general vote is in May 2014.
An EU member of 10.5 million people, the Czech Republic has been struggling to get out of a recession for the last 18 months -- its longest-ever.
The country has also been plagued by corruption since it emerged as an independent state after its 1993 split with Slovakia -- a legacy of four decades of totalitarian communist rule.
Last year, corruption watchdog Transparency International gave the country a worse ranking than Costa Rica and Rwanda.
The latest crisis erupted when Necas' chief of staff Jana Nagyova was arrested in a June 13 police swoop that included the cabinet office.
Nagyova was charged along with seven other senior figures including military intelligence heads and former lawmakers.
Prosecutors also believe she had military spies tail Necas' wife of 25 years. The prime minister announced his divorce two days before the swoop.
The country last had a caretaker government for a year after a Civic Democrat-led cabinet fell midway through its EU presidency in March 2009.