No clear victor has emerged from Romania's presidential election Sunday, exit polls suggest, making it likely that a runoff vote will be held next month.

The polls by the Insomar/Metro Media group and the Centre for Urban Sociology of Romania also indicated that no party has won a clear majority.

Twelve candidates ran for the presidency, but it narrowed down to a close race between Bucharest's mayor, Traian Basescu, and Prime Minister Adrian Nastase.

Romanian Prime Minister Adrian Nastase casts his vote together with his wife Dana in Bucharest, Romania. (AP Photo)

The exit polls gave Nastase the lead, with 43 per cent of the vote to Basescu's 35 per cent.

Official results are expected by Tuesday, but a runoff election on Dec. 12 seems likely as the winning candidate must capture more than 50 per cent of the vote.

Both men have promised to improve the standard of living in the impoverished country and to lead it into the European Union.

Nastase, an intellectual, leads the ruling Social Democratic Party that has ties to the country's communist past. He can boast that his party has brought Romania into NATO, moved it closer to membership in the EU and improved the country's economy.

Yet the EU, the United States and other international organizations have accused his party of being corrupt, interfering in the justice system and eroding media freedoms.

Basescu, a former ship's captain, is a charismatic populist known for cleaning up his city and speaking up on controversial subjects such as same-sex marriage.

He's often shamed the central government to take action on local matters, which in turn has made Basescu the target of corruption investigations and negative reporting in government-friendly media.

About 18 million people were eligible to vote in Sunday's election and slightly more than half – about 57 per cent – were expected to turn out.