Future Czech PM uncertain

The identity of the Czech Republic's future prime minister is doubtful after Social Democrats called on their leader to resign over a worse-than-expected result.

Led by Bohuslav Sobotka, the Social Democrats (CSSD) scored 20.45 per cent - down from a forecast 30 per cent. They were the largest party but finished only 1.8 percentage points ahead of the breakout populist ANO party of billionaire Andrej Babis.

Sobotka 42, was tipped as the future premier until Sunday, when he lost his place on the party's negotiating team for talks with potential coalition partners - ANO and the Christian Democrats who scored 6.8 per cent in the vote.

But he refused to step down as leader, insisting his party "took the wrong decision".

"I won't resign on the basis of today's call (for my resignation) approved by a majority in the CSSD leadership," Sobotka told reporters on Sunday.

Efforts to topple Sobotka are led by CSSD deputy chairman Michal Hasek, an ally of leftist President Milos Zeman who has been in office since March following the first-ever direct vote in the country.

Hasek and his CSSD allies secretly met with Zeman on Saturday evening without letting Sobotka know, Czech media said.

"Being optimistic, I'd say Sobotka's chances (of becoming prime minister) are marginal, they're very close to zero really," political analyst Pavel Saradin told AFP late Sunday.

"We'll see if he manages to raise significant support in the party. There may be an initiative to back him," he added.

Sobotka can be sacked by the party's central executive committee, which nominated him as party candidate for prime minister in August. The committee can meet within a week, Saradin said.

The CSSD sought a strong majority after the elections to form a minority government backed by the far-left Communists, but neither party scored enough votes to succeed.

Analysts insist any future coalition must have the support of Babis's populists to be viable.