* Voters to elect new parliament in close race
* Parliament will pick president under reforms
* Tense election may trigger unrest, analysts warn
By Hasmik Mkrtchyan
YEREVAN, April 2 (Reuters) - Armenians will elect a new parliament on Sunday in a closely fought race between the ruling party and a former coalition partner that heralds the start of a parliamentary system of government.
Under controversial constitutional reforms, parliament, rather than voters, will elect the president for the first time, and the office of prime minister will become more powerful, reducing the presidency to a largely ceremonial role.
The opposition says the changes are a ruse to let President Serzh Sarksyan slip into an enhanced prime ministerial role at the head of the ruling Republican Party of Armenia (RPA) when his presidential term ends in 2018.
Sarksyan, 62, denies the reforms were designed to extend his political career.
The outcome of Sunday's vote was difficult to predict, with polls showing the RPA neck-and-neck with an opposition alliance led by wealthy businessman Gagik Tsarukyan.
His alliance has ruled in coalition with the RPA before, but it is not clear whether it would agree to do so again if, as expected, it fails to win enough support to rule alone.
The ruling party still wields considerable support and its main campaigner, Prime Minister Karen Karapetyan, who was appointed in September, is a popular figure.
"I'll vote for the Republican Party. The new prime minister submitted a programme of changes and I think we need to give him a chance," said Susanna, a student out in central Yerevan, the capital city.
Many Armenians, however, accuse the government of corruption and mishandling the troubled economy.
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 3.0 percent in 2015.
"We need a new government, because corruption and injustice are everywhere, people aren't protected," said Suren, a 41-year-old worker.
Political analysts say unrest could erupt after the vote, partly due to a growing malaise over the economic slowdown.
"The situation is especially tense, due to the deepening level of discontent and dissent," said Richard Giragosian, director of the Regional Studies Centre in Yerevan. (Additional reporting by Margarita Antidze; Editing by Helen Popper)