Polling stations have opened in Romania in the country’s parliamentary elections.

Opinion polls suggest a large win for the governing coalition led by Prime Minister Victor Ponta and Senate President Crin Antonescu.

But the result could trigger renewed political instability as Romania negotiates a vital loan agreement with the International Monetary Fund (IMF).

Victor Ponta and so called centre-right President Traian Basescu have been bitter enemies since Ponta’s government tried to impeach the president last July.

Analysts say that, in the event of Victor Ponta’s Social Liberal Union (USL) winning, the president may ask someone other than Ponta to form a government.

President Traian Basescu has said clearly he will use his powers to appoint a prime minister “in the national interest”.

Given the enmity the president feels towards Victor Ponta and his coalition, it is hard to imagine he has the leader of the Social Liberal Union (USL) in mind.

However, any attempt to appoint someone else may result in a constitutional crisis.

If the USL wins a clear majority, analysts say the president may ask someone other than Victor Ponta from within USL to become prime minister, using the argument that the USL is not a party but a coalition.

Opinion polls in Romania suggest a large win for the governing coalition led by Prime Minister Victor Ponta

If the USL falls short of a majority, Traian Basescu could ask one of his allies in the Right Romania Alliance (ARD) to try to form a coalition.

Opinion polls have put the ARD in second place, but far away vs. USL.

Any prolonged political instability could unnerve markets and threaten a crucial IMF loan agreement.

Romania’s current loan agreement expires in early 2013.

President Traian Basescu barely survived July’s referendum on his impeachment after turnout fell below the 50% needed to validate the vote, even if 7.4 million people were against him.

He said Romanians had “rejected a coup” by staying away from polling stations.

The row between the two men has alarmed Romania’s EU partners and parlayzed political decision-making.

Romania and neighboring Bulgaria joined the EU in 2007, but Brussels has put both countries under special monitoring because of concerns about judicial independence, corruption and political influence in state institutions.