Czech President Milos Zeman has appointed Bohuslav Sobotka prime minister, opening the way for the former finance minister to pursue looser fiscal policies and closer links with the core of Europe.
The centre-left leader was named on Friday nearly three months after his Social Democrat party narrowly won an early election, and two weeks after forming a coalition with two centrist parties.
"Dear Mr Sobotka, I congratulate you on becoming the prime minister of the Czech Republic," rival leftist President Milos Zeman said at a ceremony in his Prague Castle headquarters.
The former finance minister now needs to convince long-time rival Zeman to approve his list of ministers before he can take over governance of the central European country from a caretaker cabinet that has ruled since July.
Sobotka aims to boost the economy by rolling back what he has called the "deadly spiral" of austerity measures - including cuts in spending and welfare - of the former centre-right cabinet, which collapsed under allegations of bribery and illegal surveillance last June.
He favours joining the EU's "fiscal compact" treaty on budget policy, accepted by all EU national governments except the last Czech cabinet and the United Kingdom.
Sobotka served as finance minister in 2002 to 2006, and oversaw a decline in budget deficits with the help of strong economic growth in that period.
He has been criticised by rivals for his handling of a bank and privatisations of a coal mine and an engineering firm during his term at the finance ministry, which have been subject of police investigations because of suspicions they were sold too cheaply. Sobotka has not been accused of any illegal activity.
He has also been accused of weak leadership of his party, culminating in an attempt to overthrow him after the October election.however, he has since consolidated his grip on the party.