The new Czech Prime Minister-designate, Jiri Paroubek, must keep a fractious centre-left coalition together, as tensions continue to simmer among the battered Social Democrats.
EU treaty ratification is a priority for Jiri Paroubek
His appointment ends weeks of political crisis sparked by a row over the personal finances of Stanislav Gross, who resigned on Monday.
Mr Paroubek was regional development minister in Mr Gross's cabinet.
Mr Gross - who originally studied to be a train driver - was appointed prime minister in July 2004, after a swift rise through the ranks of the Social Democrats. At 35 he became Europe's youngest prime minister.
He replaced Vladimir Spidla, who was ousted after the party's disastrous showing in the European Parliament elections.
But just six months later, Mr Gross himself was under severe pressure to resign, over a spacious apartment he bought in 1999.
A newspaper claimed his official salary was not sufficient to finance the apartment, which has an indoor swimming pool.
Mr Gross denied any wrongdoing, but his clumsy attempts to explain his personal finances only made matters worse.
Prague billboard reading: "I'm ashamed of my prime minister"
There followed allegations against his wife Sarka, whose business partner was found to be renting out a building to a brothel.
That was the last straw for Mr Gross's coalition partners, the Christian Democrats, who threatened to pull out unless he resigned. After weeks of political turmoil, the party finally left the government in late March.
That left Mr Gross with a minority Social Democrat-led cabinet, forced to rely on the unreformed Communists - untouchables in Czech politics - to survive a vote of no-confidence.
The move was seen as a further erosion of his credibility and political judgement. Ministers began leaving the cabinet in protest, leaving him with little alternative but to quit.
Mr Gross retreats to the sidelines, to prepare the ailing Social Democrats for elections next year.
Restoring the party's image will be difficult - consecutive opinion polls have shown them slipping badly.
Fall from grace
Mr Gross was once one of the country's most popular politicians, but the allegations over the apartment and his wife's business dealings badly damaged his reputation among ordinary people.
Some Czechs even took to renting special billboards featuring their own faces and the caption "I'm ashamed of my prime minister" - a reference to a disastrous local election campaign launched by Mr Gross last year.
Stanislav Gross badly mishandled the funding controversy
The previous billboards featured Mr Gross's face and the slogan "I'm a Social Democrat, and I mean that sincerely".
Months later, as the scandal deepened over his personal finances, "I mean that sincerely" became a sort of popular catchphrase. Mr Gross had become a figure of contempt, and a liability to the government.
Analysts predicted it was only a matter of time before he was forced to resign.
Mr Paroubek is seen as politically to the left of Mr Gross, although no major policy changes are expected from his government.
At the top of his agenda is ratifying the European Constitution - a complicated task in the current political climate.
The government is fearful of putting the treaty to the rather euro-apathetic Czech public. But ratification by parliament is also fraught with difficulty.
The government has a majority of just one seat in the lower house, and the constitution has many opponents. They include Czech President Vaclav Klaus, who is actively campaigning against it.
So much lies ahead for Mr Paroubek.
The Czech Republic still has to slash public spending and introduce painful reforms in healthcare, education and pension if it wants to adopt the euro by the end of the decade.
Little wonder that few analysts expect any real progress over the next 12 months.