The Czech government has suffered poor results in the first round of voting for the country’s senate.
With a third of the Parliaments upper seats at stake the opposition Social democrats won one seat out right going through to a run-off in 25 others.
The ruling Civic Democrats of Prime Minister Mirek Topolanek remain in contention for 20 seats to be decided in two weeks.
Riven with infighting Topalnek’s party could call for his head if a heavy defeat follows.
A collapse in government would raise concern over Prague’s power to take over the EU presidency in January.
The government faces difficulties over its plans to host the US missile defence plan as well as ratification of the EU’s Lisbon Treaty.