Stanislav Gross is a popular young politician

Vladimir Spidla's decision to step down in the wake of his party's poor performance in the European elections led to a collapse of government.

Mr Gross, 34, who has also taken over as head of the ruling Social Democrat Party, is a popular politician.

But correspondents say he faces an extremely difficult task.

Mr Klaus has said Mr Gross must find at least one extra vote to secure a majority in parliament and present a viable government alliance before he is formally appointed prime minister.

Speaking after a meeting with the president on Thursday, Mr Gross told reporters he wanted to build a government which would last until the 2006 elections and would not rely on communist support.

The BBC's Rob Cameron in Prague says Mr Gross is an experienced political negotiator and one of the country's most popular politicians, but if he fails in his task of forming a new coalition the Czech Republic will be one step closer to early elections.

Mr Spidla officially resigned on Thursday, weeks after a disastrous showing by the party in the European elections earlier in June apparently after alienating many traditional left-wing voters with a series of unpopular public finance reforms.

He later survived a vote of confidence within his party by a narrow margin, but decided he had lost the support of his party.