Romania election: Victor Ponta's ruling coalition wins
The centre-left coalition of Prime Minister Victor Ponta has swept to victory in Romania's general election.
The Social Liberal Union (USL) won nearly 60% of the vote, with four-fifths of ballots counted.
The Right Romania Alliance (ARD) of centre-right President Traian Basescu came a distant second with about 17%.
The result could open the door to a constitutional crisis, as the president has previously hinted he may refuse to reappoint his arch-rival Mr Ponta.
Mr Ponta said: "This is a clear victory with an absolute majority."
But, if he resumes as prime minister, he will have to share power with Mr Basescu, whose term runs until 2014.
The pair have been locked in a power struggle since Mr Ponta came to power in April following the collapse of the previous centre-right government.
The two men have argued over control of state television and the Romanian Cultural Institute and attempts to draw up a new electoral law.
But, says the BBC's correspondent in the region Nick Thorpe, the political feud often seems to have more to do with the vanity of the main players than with genuine differences in policy.
Their antagonism has meant political decision-making has at times been paralysed.
In July, Mr Ponta suspended Mr Basescu and tried to impeach him. But a referendum failed to meet the required turnout.
Mr Basescu hinted before the election that he might refuse to re-appoint Mr Ponta as prime minister. He has described him as a "mythomaniac".
Mr Basescu's popularity has plummeted since he introduced stringent austerity measures and a 25% cut in public sector pay.
Romania is the second poorest member of the European Union, which it joined in 2007 with Bulgaria.
The country, together with neighbour Bulgaria, are under special EU monitoring because of concerns about judicial independence, corruption and political influence in state institutions.
Romania is trying to negotiate a new loan from the IMF to replace the existing one which expires early next year.