YEREVAN (Reuters) - Armenia’s ruling party goes into an election on Sunday neck-and-neck in the polls with a former coalition partner, making it hard to predict the winner of a vote that will usher in a new parliamentary system of government.

FILE PHOTO: Armenia's current President Serzh Sarksyan (L) talks to the media in Yerevan, February 18, 2013. REUTERS/David Mdzinarishvili

Under constitutional changes critics say were designed to prolong the political life of President Serzh Sarksyan, parliament, not voters, will elect the president for the first time and the office of prime minister will become more powerful, with the presidency becoming a largely ceremonial role.

Sarksyan, the 62-year-old leader of the ruling Republican Party of Armenia (RPA), has repeatedly denied that the changes, which were approved by the electorate in a December 2015 referendum, were made for his benefit.

He has been president since 2008, but his current presidential term, his second, expires next year, and critics say the new system gives him some attractive options: to keep wielding executive power by becoming prime minister; to do so by simply remaining leader of the RPA; or to quit but keep exercising influence via a handpicked successor.

To be assured of having those options, Sarksyan will need his party to win Sunday’s vote, which comes as the ex-Soviet state of 3.2 million is in the grip of an economic slowdown that has sparked rising discontent.

“This election stands as a crossroads for Armenia, as either a decisive turning point or as a possibly divisive tipping point, with the country’s stability and security in the balance,” said Richard Giragosian, director of the Regional Studies Centre in the capital Yerevan.

The outcome is uncertain.

The ruling RPA is neck-and-neck in opinion polls with an opposition alliance led by a wealthy businessman, Gagik Tsarukyan. The alliance has ruled in coalition with the RPA before, but it’s unclear if it will agree to do so again if, as expected, it fails to win enough support to rule alone.

Another smaller party, which currently rules with the RPA, has said it will do a deal however, if it gets into parliament, offering the RPA a potential political lifeline.

Armenia depends heavily for aid and investment on Russia, which has been hard hit in the past three years by an economic downturn. Armenia has felt the impact, with growth falling to 0.2 percent last year from 3 percent in 2015.

Analysts say the election may be better organized than previous polls, which have been marred by irregularities, but that there is still a risk of post-election unrest.